[ubsan] Enable -fsanitize=function on Darwin

https://reviews.llvm.org/D37598

llvm-svn: 313099
diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
index 12fad3f..29fae00 100644
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -2027,6 +2027,7 @@
   Res |= SanitizerKind::Leak;
   Res |= SanitizerKind::Fuzzer;
   Res |= SanitizerKind::FuzzerNoLink;
+  Res |= SanitizerKind::Function;
   if (isTargetMacOS()) {
     if (!isMacosxVersionLT(10, 9))
       Res |= SanitizerKind::Vptr;