add 'clean' targets, make sure that 'make test' works after 'make clean'

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@48488 91177308-0d34-0410-b5e6-96231b3b80d8

test/Makefile

@@ -12,3 +12,8 @@ all::
 	PATH=$$PATH:$(ToolDir):$(LLVM_SRC_ROOT)/test/Scripts \
           find $(TESTDIRS) \( -name '*.c' -or -name '*.cpp' -or -name '*.m' \) \
 	      -print -exec ./TestRunner.sh {} \;
+
+clean::
+	rm -rf Output/
+
+.PHONY: all clean

test/Makefile.parallel

@@ -25,6 +25,7 @@ Output/%.testresults: %
 	@ PATH=$$PATH:$(ToolDir):$(LLVM_SRC_ROOT)/test/Scripts ./TestRunner.sh $< > $@ || $(REPORTFAIL)
 
 all::
+	@ mkdir -p $(addprefix Output/, $(TESTDIRS))
 	@ rm -f $(TESTS)
 	@ echo '--- Running clang tests ---'
 	@ $(MAKE) -f Makefile.parallel $(TESTS)
@@ -33,4 +34,7 @@ all::
 report: $(TESTS)
 	@ cat $^
 
-.PHONY: all report
+clean::
+	rm -rf Output/
+
+.PHONY: all report clean