Fix misspelled variable


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4262 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Makefile.rules b/Makefile.rules
index 65bb19b..e3599bb 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -432,7 +432,7 @@
 	$(VERB) $(CompileO) $< -o $@
 
 $(BUILD_ROOT)/Release/%.o: %.c $(BUILD_ROOT)/Release/.dir
-	$(VERB) $(CompileOC) $< -o $@
+	$(VERB) $(CompileCO) $< -o $@
 
 $(BUILD_ROOT)/Profile/%.o: %.cpp $(BUILD_ROOT)/Profile/.dir
 	@echo "Compiling $<"