Do not try to descend into optional build directories if they do not

exist.  This makes the build logic symmetric for both the in tree and
out of tree cases.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126070 91177308-0d34-0410-b5e6-96231b3b80d8

Makefile.rules

@@ -840,7 +840,9 @@ $(RecursiveTargets)::
 else
 $(RecursiveTargets)::
 	$(Verb) for dir in $(OPTIONAL_DIRS); do \
-	  ($(MAKE) -C$$dir $@ ) || exit 1; \
+	  if [ -d $(PROJ_SRC_DIR)/$$dir ]; then\
+	    ($(MAKE) -C$$dir $@ ) || exit 1; \
+	  fi \
 	done
 endif
 endif