Use _Exit instead of _exit in GoogleTest

_Exit is standardized since C99, whereas _exit is POSIX-only.

Fixes: #4447
PiperOrigin-RevId: 605000352
Change-Id: Ibfa84edaa043bd003a21383e8148bf45be7217f6

googlemock/src/gmock-spec-builders.cc

@@ -531,7 +531,7 @@ class MockObjectRegistry {
 #ifdef GTEST_OS_QURT
       qurt_exception_raise_fatal();
 #else
-      _exit(1);  // We cannot call exit() as it is not reentrant and
+      _Exit(1);  // We cannot call exit() as it is not reentrant and
                  // may already have been called.
 #endif
     }