[gn] Make sync script sync .mm files too

Motivated by #129332, which added a new .mm file that didn't get
autosynced.

Author: nico

llvm/utils/gn/build/sync_source_lists_from_cmake.py

@@ -61,13 +61,13 @@ def git_out(args):
     gn_files = git_out(["ls-files", "*BUILD.gn"]).splitlines()
 
     # Matches e.g. |   "foo.cpp",|, captures |foo| in group 1.
-    gn_cpp_re = re.compile(r'^\s*"([^$"]+\.(?:cpp|c|h|S))",$', re.MULTILINE)
+    gn_cpp_re = re.compile(r'^\s*"([^$"]+\.(?:cpp|c|h|mm|S))",$', re.MULTILINE)
     # Matches e.g. |   bar_sources = [ "foo.cpp" ]|, captures |foo| in group 1.
     gn_cpp_re2 = re.compile(
-        r'^\s*(?:.*_)?sources \+?= \[ "([^$"]+\.(?:cpp|c|h|S))" ]$', re.MULTILINE
+        r'^\s*(?:.*_)?sources \+?= \[ "([^$"]+\.(?:cpp|c|h|mm|S))" ]$', re.MULTILINE
     )
     # Matches e.g. |   foo.cpp|, captures |foo| in group 1.
-    cmake_cpp_re = re.compile(r"^\s*([A-Za-z_0-9./-]+\.(?:cpp|c|h|S))$", re.MULTILINE)
+    cmake_cpp_re = re.compile(r"^\s*([A-Za-z_0-9./-]+\.(?:cpp|c|h|mm|S))$", re.MULTILINE)
 
     changes_by_rev = defaultdict(lambda: defaultdict(lambda: defaultdict(list)))