Automatically create .dSYM for libcompiler_rt.dylib when using Apple's internal build system

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@168625 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/make/options.mk b/make/options.mk
index ec4a55d..67197de 100644
--- a/make/options.mk
+++ b/make/options.mk
@@ -43,5 +43,6 @@
 
 STRIP := strip
 LIPO := lipo
+DSYMUTIL := dsymutil
 
 SHARED_LIBRARY_SUFFIX := so