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)