Fix (re-)creation of unittest lit.site.cfg for clang-tools-extra.

This has been hiding really well. Hopefully brings the builders suffering from
outdated lit.site.cfg files back to life.

llvm-svn: 215575

Author: d0k

llvm/test/Makefile

@@ -57,7 +57,7 @@ LIT_ALL_TESTSUITES += $(PROJ_OBJ_DIR)/../tools/clang/tools/extra/test
 
 # Force creation of Clang Tools' lit.site.cfg.
 clang-tools-site-cfg: FORCE
-	$(MAKE) -C $(PROJ_OBJ_DIR)/../tools/clang/tools/extra/test lit.site.cfg
+	$(MAKE) -C $(PROJ_OBJ_DIR)/../tools/clang/tools/extra/test lit.site.cfg Unit/lit.site.cfg
 extra-site-cfgs:: clang-tools-site-cfg
 endif