Make -j8 safe.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67252 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Makefile b/lib/Driver/Makefile
index c47bf62..7993279 100644
--- a/lib/Driver/Makefile
+++ b/lib/Driver/Makefile
@@ -18,7 +18,7 @@
 
 include $(LEVEL)/Makefile.common
 
-.ver:
+$(ObjDir)/.ver-svn .ver:
 	@if [ '$(SVN_REVISION)' != '$(shell cat $(ObjDir)/.ver-svn 2>/dev/null)' ]; then\
 		echo '$(SVN_REVISION)' > $(ObjDir)/.ver-svn;			\
 	fi