tools: make utils.SearchFiles deterministic

glob.glob on Linux returns files in the order returned by the filesystem driver,
and the output from this function is stuffed by the Electron build process
straight into the config.gypi header, causing non-reproducible builds.

See this log for an example of the nondeterminism:
https://rb.zq1.de/compare.factory-20220901/diffs/nodejs-electron-compare.out

tools/utils.py

@@ -112,4 +112,4 @@ def SearchFiles(dir, ext):
   list = glob.glob(dir+ '/**/*.' + ext, recursive=True)
   if sys.platform == 'win32':
     list = [ x.replace('\\', '/')for x in list]
-  return list
+  return sorted(list)