druntime/dmain2: disable RTSan monitoring in init_rt ...

... this function is not real-time safe and also not rtsan safe (will
lock-up rtsan's stack scanner)

Author: liushuyu

runtime/druntime/src/rt/dmain2.d

@@ -70,6 +70,15 @@ extern (C) void thread_joinAll();
 extern (C) UnitTestResult runModuleUnitTests();
 extern (C) void _d_initMonoTime() @nogc nothrow;
 
+version (SupportSanitizers)
+{
+    import ldc.attributes;
+
+    @weak extern (C) void __rtsan_disable() @nogc nothrow {}
+    @weak extern (C) void __rtsan_enable() @nogc nothrow {}
+    @weak extern (C) void __rtsan_notify_blocking_call(const char* name) @nogc nothrow {}
+}
+
 version (CRuntime_Microsoft)
 {
     extern(C) void init_msvc();
@@ -103,6 +112,12 @@ private shared size_t _initCount;
  */
 extern (C) int rt_init()
 {
+    version (SupportSanitizers)
+    {
+        __rtsan_notify_blocking_call("rt_init");
+        __rtsan_disable();
+        scope (exit) __rtsan_enable();
+    }
     /* @@BUG 11380 @@ Need to synchronize rt_init/rt_term calls for
        version (Shared) druntime, because multiple C threads might
        initialize different D libraries without knowing about the