Auto merge of #13518 - upsuper:patch-1, r=emilio

Move --use-msvc-mangling out from clang flags.

`--use-msvc-mangling` is not a clang flag, but a flag for bindgen.

r? @emilio

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components/style/binding_tools/regen.py

@@ -270,7 +270,6 @@ def platform_dependent_defines():
     elif system == "Windows":
         ret.append("-DOS_WIN=1")
         ret.append("-DWIN32=1")
-        ret.append("-use-msvc-mangling")
         msvc_platform = os.environ["PLATFORM"]
         if msvc_platform == "X86":
             ret.append("--target=i686-pc-win32")
@@ -392,6 +391,9 @@ def build(objdir, target_name, debug, debugger, kind_name=None,
 
     clang_flags.extend(platform_dependent_defines())
 
+    if platform.system() == "Windows":
+        flags.append("--use-msvc-mangling")
+
     if "raw_lines" in current_target:
         for raw_line in current_target["raw_lines"]:
             flags.append("--raw-line")