[hwasan] provide a runtime flag for printing remaining threads in error report as an extra information

[Enna1]

Summary

This patch adds a runtime flag print_live_threads_info, which defaults to true, controls whether or not prints remaining threads in error report as an extra information.
We(ByteDance) are in the process of enabling hwasan for our server-side applications on AArch64/Linux, these server-side applications have thousands of threads, so it is nice to have this option.

[Enna1]

clang-format

compiler-rt/lib/hwasan/hwasan_flags.inc

 
 HWASAN_FLAG(bool, verbose_threads, false,
             "inform on thread creation/destruction")
 HWASAN_FLAG(bool, tag_in_malloc, true, "")
 HWASAN_FLAG(bool, tag_in_free, true, "")
 HWASAN_FLAG(bool, print_stats, false, "")
 HWASAN_FLAG(bool, halt_on_error, true, "")
 HWASAN_FLAG(bool, atexit, false, "")
+HWASAN_FLAG(
+    bool, print_live_threads_info, true,
+    "If set, prints the remaining threads in report as an extra information.")
 
 // Test only flag to disable malloc/realloc/free memory tagging on startup.
 // Tagging can be reenabled with __hwasan_enable_allocator_tagging().
 HWASAN_FLAG(bool, disable_allocator_tagging, false, "")
 
 // If false, use simple increment of a thread local counter to generate new
 // tags.
 HWASAN_FLAG(bool, random_tags, true, "")

compiler-rt/lib/hwasan/hwasan_report.cpp

void PrintAddressDescription(
   });
 
   if (candidate && num_descriptions_printed == 0) {
     ShowHeapOrGlobalCandidate(untagged_addr, candidate, left, right);
     num_descriptions_printed++;
   }
 
   // Print the remaining threads, as an extra information, 1 line per thread.
+  if (flags()->print_live_threads_info)
     hwasanThreadList().VisitAllLiveThreads([&](Thread *t) { t->Announce(); });
 
   if (!num_descriptions_printed)
     // We exhausted our possibilities. Bail out.
     Printf("HWAddressSanitizer can not describe address in more detail.\n");
   if (num_descriptions_printed > 1) {
     Printf(
         "There are %d potential causes, printed above in order "
         "of likeliness.\n",