sanitizer_common: avoid compiler-interted memset in deadlock detector

[dvyukov]

Summary

Compilers tends to insert memset/memcpy for some struct/array operations,
and these don't play well inside of sanitizer runtimes.
Avoiding these calls was the intention behind internal_memset.
Remove the leftover ={} that can result in memset call.

[pgousseau]

Lgtm! Thank you for the quick fix!

compiler-rt/lib/sanitizer_common/sanitizer_mutex.cpp

 static bool mutex_can_lock[kMutexTypeMax][kMutexTypeMax];
 // Mutex types with MutexMulti mark.
 static bool mutex_multi[kMutexTypeMax];
 
 void DebugMutexInit() {
   // Build adjacency matrix.
   bool leaf[kMutexTypeMax];
   internal_memset(&leaf, 0, sizeof(leaf));
-  int cnt[kMutexTypeMax] = {};
+  int cnt[kMutexTypeMax];
   internal_memset(&cnt, 0, sizeof(cnt));
   for (int t = 0; t < kMutexTypeMax; t++) {
     mutex_type_count = t;
     if (!mutex_meta[t].name)
       break;
     CHECK_EQ(t, mutex_meta[t].type);
     for (uptr j = 0; j < ARRAY_SIZE(mutex_meta[t].can_lock); j++) {
       MutexType z = mutex_meta[t].can_lock[j];