This eliminates the landmines hook.

build/landmines.py writes out a .landmines file at the root of the
buildroot. The first step of a `gclient sync` is to check for diffs
between that file and the new one, and if found, a clobber is performed.

We never actually use this functionality, and the code calls rmtree()
which (at least on macos) appears to choke on symlinks.

This deletes these scripts, and will be paired with the deletion of the
first gclient hook in the DEPS file in flutter/engine during the roll.

If we ever need this functionality, it's relatively straightforward to
add it back.

Issue: flutter/flutter#87960

At one point, this shard built the Android Vulkan binaries, but during
the migration to ci.yaml-based recipes, the gn and build steps for that
build were accidentally removed. As such, this shard no longer builds
anything.

This was detected when a buildroot roll triggered a clobber build which
caused the verify_exported.dart script to fail due to a missing 'out'
directory, which caused several of us to wonder why we were:
1. Checking that we strip release binaries on a debug bot, and
2. Why we're checking that we strip release binaries before we actually
   build anything at all.

It appears that we used to build android vulkan binaries, such as in
steps 14-16 of Build 11130:
* https://ci.chromium.org/ui/p/flutter/builders/prod/Mac%20Android%20Debug%20Engine/11130/overview

We migrated to ci.yaml-based infra in this commit:
* https://flutter-review.googlesource.com/c/infra/+/15660

A no-op rebuild was triggered in commmit:
* https://github.com/flutter/engine/pull/27599

Which triggered the following buikld, Build 11131:
* https://ci.chromium.org/ui/p/flutter/builders/prod/Mac%20Android%20Debug%20Engine/11131/overview

That build does not contain the gn or build steps for the Android Vulkan
binaries.

HOWEVER... we have no users actually using Android Vulkan binaries, so
rather than update the build to fix this, we delete the shard altogether
and save some CPU.

This will be followed by a patch that removes the --enable-vulkan flag
from gn and throughout our build.

Since verify_exported.dart is not run with assertions enabled, replace
the assertions with runtime checks and appropriate error messages:

* Adds a check for valid arguments and emits usage otherwise
* Adds a check for the presence of the out/ directory and exits with
  error if it does not exist.

This just fixes a couple of minor analyzer errors in the sample code so that they won't break the build when I fix the analyzer in the flutter repo.

Fix the SurfaceTexture related crash by Replacing the JNI weak global reference with a WeakReference<SurfaceTexture> (#27924)

* Fix routerinformationupdate can take complex json

* comment