Bug 1776461 - Don't define the WIN32 and _WIN32_IE macros in mozilla-config.h if they're already defined. r=firefox-build-system-reviewers,ahochheiden

Differential Revision: https://phabricator.services.mozilla.com/D150268

python/mozbuild/mozbuild/action/process_define_files.py

@@ -60,7 +60,7 @@ def process_define_file(output, input):
                             redefinition warnings.  Just handle those macros
                             specially here."""
                             define = "#define {name} {val}".format(name=name, val=val)
-                            if name in ("WINVER", "_WIN32_WINNT"):
+                            if name in ("_WIN32_IE", "_WIN32_WINNT", "WIN32", "WINVER"):
                                 return "#if !defined({name})\n{define}\n#endif".format(
                                     name=name, define=define
                                 )