Remove TESTDIR initialization, MultiTestRunner can find the test dirs itself.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@77069 91177308-0d34-0410-b5e6-96231b3b80d8

test/Makefile

@@ -2,7 +2,7 @@ LEVEL = ../../..
 include $(LEVEL)/Makefile.common
 
 # Test in all immediate subdirectories if unset.
-TESTDIRS ?= $(shell echo $(PROJ_SRC_DIR)/*/)
+TESTDIRS ?= .
 
 ifndef TESTARGS
 ifdef VERBOSE