[libFuzzer] don't print bogus error message

llvm-svn: 277940
diff --git a/llvm/lib/Fuzzer/FuzzerLoop.cpp b/llvm/lib/Fuzzer/FuzzerLoop.cpp
index 9c71562..ebcf892 100644
--- a/llvm/lib/Fuzzer/FuzzerLoop.cpp
+++ b/llvm/lib/Fuzzer/FuzzerLoop.cpp
@@ -129,8 +129,9 @@
       C->PcBufferPos = NewPcBufferPos;
     }
 
-    if (NewPcBufferPos >= PcBufferLen) {
-      Printf("ERROR: PC buffer overflow.\n");
+    if (PcBufferLen && NewPcBufferPos >= PcBufferLen) {
+      Printf("ERROR: PC buffer overflow\n");
+      _Exit(1);
     }
 
     return Res;