drcachesim offline fails on fork child with error about file creation

[derekbruening]

I first hit this tracing SPEC2017 perlbench.
I can reproduce it easily:

$ bin64/drrun -t drcachesim -offline -- suite/tests/bin/linux.fork
parent is running under DynamoRIO
<-- parent 564285 forked child 564286 -->
Failed to create new thread file for window ./drmemtrace.linux.fork.564286.0539.dir/raw/drmemtrace.linux.fork.564286.7156.raw.lz4

[derekbruening]

Xref a malloc check issue with fork (maybe that would be hit after this error is fixed): https://groups.google.com/g/dynamorio-users/c/D0HTG6dDIsY

[derekbruening]

I see two further issues with -satisfy_w_xor_x:

$ bin64/drrun -satisfy_w_xor_x -t drcachesim -verbose 2 -offline -- suite/tests/bin/linux.fork
Log directory is ./drmemtrace.linux.fork.610987.1941.dir/raw
Created thread trace file ./drmemtrace.linux.fork.610987.1941.dir/raw/drmemtrace.linux.fork.610987.0405.raw.lz4
<curiosity: rex.w on OPSZ_6_irex10_short4!>
<spurious rep/repne prefix @0x00007f3985f5a280 (f3 0f 1e fa): >
parent is running under DynamoRIO
<-- parent 610987 forked child 610988 -->
Log directory is ./drmemtrace.linux.fork.610988.1368.dir/raw
<CURIOSITY : !present && "stale fd not cleaned up" in file /home/bruening/dr/git/src/core/unix/os.c line 4179...>
Created thread trace file ./drmemtrace.linux.fork.610988.1368.dir/raw/drmemtrace.linux.fork.610988.5573.raw.lz4
parent waiting for child
child is running under DynamoRIO
<Stopping application /home/bruening/dr/git/build_x64_dbg_tests/suite/tests/bin/linux.fork (610988)>
drmemtrace exiting process 610988; traced 939577 references.
<Application /home/bruening/dr/git/build_x64_dbg_tests/suite/tests/bin/linux.fork (610988).  Internal Error: DynamoRIO debug check failure: /home/bruening/dr/git/src/core/utils.c:1566 !bitmap_test(b, first_block)
(Error occurred @3682 frags in tid 610988)...>

[derekbruening]

The first is a failure to remove the dual_map_file from the protected fd table.