libFuzzer, OpenBSD support

Summary:
- Enabling libfuzzer on OpenBSD
- OpenBSD can t support asan, msan ... the tests can t be run.

Patch by David CARLIER

Reviewers: eugenis, phosek, vitalybuka

Reviewed By: vitalybuka

Subscribers: srhines, mgorny, krytarowski, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D44877

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@329631 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/FuzzerUtilPosix.cpp b/FuzzerUtilPosix.cpp
index cef6cec..bc64d32 100644
--- a/FuzzerUtilPosix.cpp
+++ b/FuzzerUtilPosix.cpp
@@ -118,7 +118,8 @@
   struct rusage usage;
   if (getrusage(RUSAGE_SELF, &usage))
     return 0;
-  if (LIBFUZZER_LINUX || LIBFUZZER_FREEBSD || LIBFUZZER_NETBSD) {
+  if (LIBFUZZER_LINUX || LIBFUZZER_FREEBSD || LIBFUZZER_NETBSD ||
+      LIBFUZZER_OPENBSD) {
     // ru_maxrss is in KiB
     return usage.ru_maxrss >> 10;
   } else if (LIBFUZZER_APPLE) {