Trigger new builds of libimobiledevice, libimobiledeviceglue, and libusbmuxd

[jmagman]

libimobiledevice, libimobiledeviceglue, and libusbmuxd builds need to be triggered in order to build fat ARM/x64 binaries after https://flutter-review.googlesource.com/c/recipes/+/73060. However, there's no newer commit than the one we're already mirroring.

One possible solution is to push an empty commit to a branch, and point the recipe to that branch.

Note the libimobiledeviceglue part is blocked on #182585.

[jtmcdole]

Mentioned in conversation:

One possible solution is to push an empty commit to a branch, and point the recipe to that branch.

This would break the mirror and we'd need to have a branch that the empty comment went to.

[jmagman]

New flutter branches with empty commits:

• https://flutter-review.googlesource.com/c/third_party/libimobiledevice/+/77481
• https://flutter-review.googlesource.com/c/third_party/libimobiledevice-glue/+/77500
• https://flutter-review.googlesource.com/c/third_party/libusbmuxd/+/77480

Recipe change to check out the flutter branch:
https://flutter-review.googlesource.com/c/recipes/+/77520?tab=checks

[jmagman]

libimobiledeviceglue triggered c1be125a7366458516b6c9dfeb7df0a5e513f9a4 and includes arm64: https://ci.chromium.org/ui/p/dart-internal/builders/flutter/Mac%20ios_usb_dependencies_release/64/overview
flutter branch: https://source.corp.google.com/h/flutter/third_party/libimobiledevice-glue/+/flutter:

However libimobiledevice and libusbmuxd are missing the flutter branch:
https://source.corp.google.com/h/flutter/third_party/libimobiledevice/+/flutter:
https://source.corp.google.com/h/flutter/third_party/libusbmuxd/+/flutter:

[Edit: Jason set the remote_config.fetch_remove_deleted flag to false on all of these repositories and restored the flutter branches.]

[jmagman]

The new branches are present, and the binaries built: https://ci.chromium.org/ui/p/dart-internal/builders/flutter/Mac%20ios_usb_dependencies_release/65/overview