improve sourceflags for cl #6898

Author: waruqi

xmake/modules/core/tools/cl.lua

@@ -447,7 +447,7 @@ function add_sourceflags(self, sourcefile, fileconfig, target, targetkind)
     --   add_files("*.c", {sourcekind = "cxx"})
     --
     local sourcekind = fileconfig.sourcekind
-    if sourcekind and sourcekind ~= language.sourcekind_of(sourcefile) then
+    if sourcekind then
         local maps = {cc = "-TC", cxx = "-TP"}
         return maps[sourcekind]
     end