c-index-test Makefile: fix build on Linux. Reviewed by Eric Christopher.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161439 91177308-0d34-0410-b5e6-96231b3b80d8

tools/c-index-test/Makefile

@@ -29,5 +29,5 @@ USEDLIBS = clang.a clangFrontend.a clangDriver.a \
 
 include $(CLANG_LEVEL)/Makefile
 
-LIBS += "$(LIBXML2_LIBS)"
-CPPFLAGS += "$(LIBXML2_INC)"
+LIBS += $(LIBXML2_LIBS)
+CPPFLAGS += $(LIBXML2_INC)