Revert "[libFuzzer tests] Use substring comparison in libFuzzer tests"

This reverts commit 3592d8049660dcdd07f7c2e797f2de9790f93111.

Breaks the bots, reverting for now.

llvm-svn: 309899

llvm/lib/Fuzzer/test/InitializeTest.cpp

@@ -20,7 +20,7 @@ extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv) {
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
   if (Size == strlen(argv0) &&
-      !strnstr(reinterpret_cast<const char *>(Data), argv0, Size)) {
+      !strncmp(reinterpret_cast<const char *>(Data), argv0, Size)) {
     fprintf(stderr, "BINGO %s\n", argv0);
     exit(1);
   }