Delete unused create_macos_gen_snapshot.py script (flutter/engine#10479)

Unused as of https://github.com/flutter/engine/pull/10430 and
https://chromium-review.googlesource.com/c/chromium/tools/build/+/1731443.

engine/src/flutter/sky/tools/create_macos_gen_snapshot.py

@@ -1,45 +0,0 @@
-#!/usr/bin/env python
-# Copyright 2013 The Flutter Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-import argparse
-import subprocess
-import sys
-import os
-
-
-def main():
-  parser = argparse.ArgumentParser(description='Creates multi-arch gen_snapshot')
-
-  parser.add_argument('--dst', type=str, required=True)
-  parser.add_argument('--arm64-out-dir', type=str, required=True)
-  parser.add_argument('--armv7-out-dir', type=str, required=True)
-
-  args = parser.parse_args()
-
-  fat_gen_snapshot = os.path.join(args.dst, 'gen_snapshot')
-  arm64_gen_snapshot = os.path.join(args.arm64_out_dir, 'clang_x64', 'gen_snapshot')
-  armv7_gen_snapshot = os.path.join(args.armv7_out_dir, 'clang_x64', 'gen_snapshot')
-
-  if not os.path.isfile(arm64_gen_snapshot):
-    print 'Cannot find x86_64 (arm64) gen_snapshot at', arm64_gen_snapshot
-    return 1
-
-  if not os.path.isfile(armv7_gen_snapshot):
-    print 'Cannot find i386 (armv7) gen_snapshot at', armv7_gen_snapshot
-    return 1
-
-  subprocess.check_call([
-    'lipo',
-    arm64_gen_snapshot,
-    armv7_gen_snapshot,
-    '-create',
-    '-output',
-    fat_gen_snapshot,
-  ])
-
-
-if __name__ == '__main__':
-  sys.exit(main())
-