[TRIVIAL] std.experimental.logger...: Fix -dip1000 compilable issues

[carblue]

Using posix.mak from #6195
with aa[std.experimental.logger.core]=-dip1000 and running
make -f posix.mak std/experimental/logger/core.test
results in:
...

T=`mktemp -d /tmp/.dmd-run-test.XXXXXX` &&                                                              \
  (                                                                                                     \
    ../dmd/generated/linux/release/64/dmd -od$T -conf= -I../druntime/import  -w -de -dip25 -m64 -fPIC -transition=complex -O -release -dip1000  -main -unittest generated/linux/release/64/libphobos2.a -defaultlib= -debuglib= -L-ldl -cov -run std/experimental/logger/core.d ;     \
    RET=$? ; rm -rf $T ; exit $RET                                                                   \
  )
std/experimental/logger/core.d(654): Error: reference to local variable buffer assigned to non-scope parameter msg calling std.experimental.logger.core.Logger.logMsgPart
std/experimental/logger/core.d(674): Error: @safe function std.experimental.logger.core.__unittest_L668_C9.dummy cannot call @system function std.experimental.logger.core.formatString!(string, string).formatString
std/experimental/logger/core.d(1852): Error: @safe function std.experimental.logger.core.testFuncNames cannot call @system function std.experimental.logger.core.Logger.log!string.log
std/experimental/logger/core.d(1894): Error: @safe function std.experimental.logger.core.__unittest_L1866_C7 cannot call @system function std.experimental.logger.core.log!(LogLevel).log
std/experimental/logger/core.d(1919): Error: @safe function std.experimental.logger.core.__unittest_L1907_C7 cannot call @system function std.experimental.logger.core.Logger.log!string.log
std/experimental/logger/core.d(1952): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.Logger.log!string.log
std/experimental/logger/core.d(1958): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.Logger.log!string.log
std/experimental/logger/core.d(1964): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.Logger.log!string.log
std/experimental/logger/core.d(1970): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.Logger.logf!(1970, "std/experimental/logger/core.d", "std.experimental.logger.core.__unittest_L1944_C7", "void std.experimental.logger.core.__unittest_L1944_C7() @safe", "std.experimental.logger.core", string).logf
std/experimental/logger/core.d(1976): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.Logger.logf!(1976, "std/experimental/logger/core.d", "std.experimental.logger.core.__unittest_L1944_C7", "void std.experimental.logger.core.__unittest_L1944_C7() @safe", "std.experimental.logger.core", string).logf
std/experimental/logger/core.d(1982): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.Logger.logf!(1982, "std/experimental/logger/core.d", "std.experimental.logger.core.__unittest_L1944_C7", "void std.experimental.logger.core.__unittest_L1944_C7() @safe", "std.experimental.logger.core", string).logf
std/experimental/logger/core.d(2003): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.Logger.logf!(2003, "std/experimental/logger/core.d", "std.experimental.logger.core.__unittest_L1944_C7", "void std.experimental.logger.core.__unittest_L1944_C7() @safe", "std.experimental.logger.core", string).logf
std/experimental/logger/core.d(2028): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.log!string.log
std/experimental/logger/core.d(2034): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.log!(string, "std.experimental.logger.core").log
std/experimental/logger/core.d(2040): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.log!(string, "std.experimental.logger.core").log
std/experimental/logger/core.d(2046): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.logf!(2046, "std/experimental/logger/core.d", "std.experimental.logger.core.__unittest_L1944_C7", "void std.experimental.logger.core.__unittest_L1944_C7() @safe", "std.experimental.logger.core", string).logf
std/experimental/logger/core.d(2052): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.logf!(2052, "std/experimental/logger/core.d", "std.experimental.logger.core.__unittest_L1944_C7", "void std.experimental.logger.core.__unittest_L1944_C7() @safe", "std.experimental.logger.core", string).logf
std/experimental/logger/core.d(2058): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.logf!(2058, "std/experimental/logger/core.d", "std.experimental.logger.core.__unittest_L1944_C7", "void std.experimental.logger.core.__unittest_L1944_C7() @safe", "std.experimental.logger.core", string).logf
std/experimental/logger/core.d(2080): Error: @safe function std.experimental.logger.core.__unittest_L1944_C7 cannot call @system function std.experimental.logger.core.logf!(2080, "std/experimental/logger/core.d", "std.experimental.logger.core.__unittest_L1944_C7", "void std.experimental.logger.core.__unittest_L1944_C7() @safe", "std.experimental.logger.core", string).logf
std/experimental/logger/core.d(2167): Error: @safe function std.experimental.logger.core.__unittest_L2161_C7 cannot call @system function std.experimental.logger.core.Logger.memLogFunctions!cast(LogLevel)cast(ubyte)64u.logImpl!(2167, "std/experimental/logger/core.d", "std.experimental.logger.core.__unittest_L2161_C7", "void std.experimental.logger.core.__unittest_L2161_C7() @safe", "std.experimental.logger.core", string).logImpl
posix.mak:570: (the rule for target „std/experimental/logger/core.test“ failed) die Regel für Ziel „std/experimental/logger/core.test“ scheiterte

With PR applied (and std.experimental.logger.core. formatString and systimeToISOString TEMPORARILY ATTRIBUTED @safe), the remaining errors are:
A known one, https://issues.dlang.org/show_bug.cgi?id=17961 / #6041 from std.uni and unsolved ones from std.format.formattedWrite

[dlang-bot]

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[wilzbach]

Thanks