[libFuzzer] be more robust when dealing with files on disk (e.g. don't crash if a file was there but disappeared)

llvm-svn: 247066
diff --git a/llvm/lib/Fuzzer/FuzzerIO.cpp b/llvm/lib/Fuzzer/FuzzerIO.cpp
index a68c6c5..b6ffb75 100644
--- a/llvm/lib/Fuzzer/FuzzerIO.cpp
+++ b/llvm/lib/Fuzzer/FuzzerIO.cpp
@@ -21,10 +21,8 @@
 
 static long GetEpoch(const std::string &Path) {
   struct stat St;
-  if (stat(Path.c_str(), &St)) {
-    Printf("Can not stat: %s; exiting\n", Path.c_str());
-    exit(1);
-  }
+  if (stat(Path.c_str(), &St))
+    return 0;  // Can't stat, be conservative.
   return St.st_mtime;
 }