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/afl/afl_driver.cpp b/afl/afl_driver.cpp
index 1d1c16a..9f50ddd 100644
--- a/afl/afl_driver.cpp
+++ b/afl/afl_driver.cpp
@@ -70,21 +70,31 @@
 #define LIBFUZZER_APPLE 0
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #elif __APPLE__
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_APPLE 1
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #elif __NetBSD__
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_APPLE 0
 #define LIBFUZZER_NETBSD 1
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #elif __FreeBSD__
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_APPLE 0
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 1
+#define LIBFUZZER_OPENBSD 0
+#elif __OpenBSD__
+#define LIBFUZZER_LINUX 0
+#define LIBFUZZER_APPLE 0
+#define LIBFUZZER_NETBSD 0
+#define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 1
 #else
 #error "Support for your platform has not been implemented"
 #endif
@@ -133,7 +143,8 @@
   struct rusage usage;
   if (getrusage(RUSAGE_SELF, &usage))
     return 0;
-  if (LIBFUZZER_LINUX || LIBFUZZER_NETBSD || LIBFUZZER_FREEBSD) {
+  if (LIBFUZZER_LINUX || LIBFUZZER_NETBSD || LIBFUZZER_FREEBSD ||
+      LIBFUZZER_OPENBSD) {
     // ru_maxrss is in KiB
     return usage.ru_maxrss >> 10;
   } else if (LIBFUZZER_APPLE) {