[libFuzzer] experimental performance optimization -lazy_counters, off by default. Posix-only for now, tested on Linux

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@352700 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/FuzzerOptions.h b/FuzzerOptions.h
index ef89754..3f8e959 100644
--- a/FuzzerOptions.h
+++ b/FuzzerOptions.h
@@ -67,6 +67,7 @@
   bool HandleXfsz = false;
   bool HandleUsr1 = false;
   bool HandleUsr2 = false;
+  bool LazyCounters = false;
 };
 
 }  // namespace fuzzer