fix optimization-disabled test builds with platform010 (facebook#11361)

Summary:
Fixed the following failure:

```
third-party/gtest-1.8.1/fused-src/gtest/gtest-all.cc: In function ‘bool testing::internal::StackGrowsDown()’:
third-party/gtest-1.8.1/fused-src/gtest/gtest-all.cc:8681:24: error: ‘dummy’ may be used uninitialized [-Werror=maybe-uninitialized]
 8681 |   StackLowerThanAddress(&dummy, &result);
      |   ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
third-party/gtest-1.8.1/fused-src/gtest/gtest-all.cc:8671:13: note: by argument 1 of type ‘const void*’ to ‘void testing::internal::StackLowerThanAddress(const void*, bool*)’ declared here
 8671 | static void StackLowerThanAddress(const void* ptr, bool* result) {
      |             ^~~~~~~~~~~~~~~~~~~~~
third-party/gtest-1.8.1/fused-src/gtest/gtest-all.cc:8679:7: note: ‘dummy’ declared here
 8679 |   int dummy;
      |       ^~~~~
```

Pull Request resolved: facebook#11361

Reviewed By: cbi42

Differential Revision: D44838033

Pulled By: ajkr

fbshipit-source-id: 27d68b5a24a15723bbaaa7de45ccd70a60fe259e

Author: ajkr

third-party/gtest-1.8.1/fused-src/gtest/gtest-all.cc

@@ -8676,7 +8676,7 @@ static void StackLowerThanAddress(const void* ptr, bool* result) {
 // Make sure AddressSanitizer does not tamper with the stack here.
 GTEST_ATTRIBUTE_NO_SANITIZE_ADDRESS_
 static bool StackGrowsDown() {
-  int dummy;
+  int dummy = 0;
   bool result;
   StackLowerThanAddress(&dummy, &result);
   return result;