[Tsan] Do not sanitize memset() and other functions during initialization

[kutuzov.viktor.84]

Summary

We need these to suppress to pass initialization on FreeBSD 11.
Duplicates D8543 due to missed llvm-commits.

[kutuzov.viktor.84]

Updated as suggested in D8543#inline-69954.

Is this fix testable? or is it covered by existing tests?

This fix resolves mass failures on FreeBSD 11, see the "alignment != 0" lines at:
http://lab.llvm.org:8011/builders/sanitizer_x86_64-freebsd/builds/4831/steps/make-check-tsan/logs/stdio

[kcc]

LGTM

lib/tsan/rtl/tsan_interceptors.cc

 #elif defined(__mips__)
 const int SA_SIGINFO = 8;
 const int SIG_SETMASK = 3;
 #else
 const int SA_SIGINFO = 4;
 const int SIG_SETMASK = 2;
 #endif
 
+#define COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED \
+  (!cur_thread()->is_inited)
+
 namespace std {
 struct nothrow_t {};
 }  // namespace std
 
 static sigaction_t sigactions[kSigCount];
 
 namespace __tsan {
 struct SignalDesc {

 TSAN_INTERCEPTOR(uptr, strlen, const char *s) {
   SCOPED_TSAN_INTERCEPTOR(strlen, s);
   uptr len = internal_strlen(s);
   MemoryAccessRange(thr, pc, (uptr)s, len + 1, false);
   return len;
 }
 
 TSAN_INTERCEPTOR(void*, memset, void *dst, int v, uptr size) {
+  // On FreeBSD we get here from libthr internals on thread initialization.
+  if (!COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED) {
     SCOPED_TSAN_INTERCEPTOR(memset, dst, v, size);
     MemoryAccessRange(thr, pc, (uptr)dst, size, true);
+  }
   return internal_memset(dst, v, size);
 }
 
 TSAN_INTERCEPTOR(void*, memcpy, void *dst, const void *src, uptr size) {
   // On FreeBSD we get here from libthr internals on thread initialization.
-  if (cur_thread()->is_inited) {
+  if (!COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED) {
     SCOPED_TSAN_INTERCEPTOR(memcpy, dst, src, size);
     MemoryAccessRange(thr, pc, (uptr)dst, size, true);
     MemoryAccessRange(thr, pc, (uptr)src, size, false);
   }
   return internal_memcpy(dst, src, size);
 }
 
 TSAN_INTERCEPTOR(int, memcmp, const void *s1, const void *s2, uptr n) {