Add CXXFLAGS back to the Link command.

This is essentially reverting one piece of 184793 to try to fix one of Apple's
buildbots.  I will check with Eric to see if this is OK or if we need to find
some other solution.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185060 91177308-0d34-0410-b5e6-96231b3b80d8

Makefile.rules

@@ -757,7 +757,8 @@ Preprocess.CXX= $(Compile.Wrapper) \
 	          $(CXX) $(CPP.Flags) $(TargetCommonOpts) $(CPPFLAGS) \
                 $(CompileCommonOpts) $(CXX.Flags) -E
 Link          = $(Compile.Wrapper) \
-	          $(CXX) $(LD.Flags) $(LDFLAGS) $(TargetCommonOpts) $(Strip)
+	          $(CXX) $(CXXFLAGS) $(LD.Flags) $(LDFLAGS) \
+                $(TargetCommonOpts) $(Strip)
 
 BCCompile.C   = $(LLVMCC) $(CPP.Flags) $(C.Flags) $(CFLAGS) $(CPPFLAGS) \
                 $(TargetCommonOpts) $(CompileCommonOpts)