Revert "[compiler-rt] Add a critical section when flushing gcov counters"

See the discussion on PR44792.

This reverts commit 02ce9d8.

Author: zmodem

compiler-rt/lib/profile/GCDAProfiling.c

@@ -62,27 +62,8 @@ typedef unsigned long long uint64_t;
 #include "InstrProfiling.h"
 #include "InstrProfilingUtil.h"
 
-#ifndef _WIN32
-#include <pthread.h>
-static pthread_mutex_t gcov_flush_mutex = PTHREAD_MUTEX_INITIALIZER;
-static __inline void gcov_flush_lock() {
-  pthread_mutex_lock(&gcov_flush_mutex);
-}
-static __inline void gcov_flush_unlock() {
-  pthread_mutex_unlock(&gcov_flush_mutex);
-}
-#else
-#include <windows.h>
-static SRWLOCK gcov_flush_mutex = SRWLOCK_INIT;
-static __inline void gcov_flush_lock() {
-  AcquireSRWLockExclusive(&gcov_flush_mutex);
-}
-static __inline void gcov_flush_unlock() {
-  ReleaseSRWLockExclusive(&gcov_flush_mutex);
-}
-#endif
-
 /* #define DEBUG_GCDAPROFILING */
+
 /*
  * --- GCOV file format I/O primitives ---
  */
@@ -639,16 +620,12 @@ void llvm_register_flush_function(fn_ptr fn) {
 }
 
 void __gcov_flush() {
-  gcov_flush_lock();
-
   struct fn_node* curr = flush_fn_list.head;
 
   while (curr) {
     curr->fn();
     curr = curr->next;
   }
-
-  gcov_flush_unlock();
 }
 
 COMPILER_RT_VISIBILITY