Update git submodules

* Update libcore from branch 'master'
  to c305f5e3bbcd6a6296497a60ef51f78431383b85
  - Merge "Use prebuilt bpfmt in upload hook"
  - Use prebuilt bpfmt in upload hook
    
    The bpfmt tool will not always be on the path, e.g. if it has not been
    compiled. This switches to use the version that is available in
    prebuilts/build-tools/... The path to the bpfmt executable is passed in
    to the check-bpfmt.sh script because it depends on the ${BUILD_OS}
    placeholder. See tools/repohooks/README.md for more information about
    placeholders.
    
    Test: attempted to upload change with badly formatted .bp file.
    Change-Id: I4d0d12ed9ef533dae7e47d4ea9d840585d831a3b
    
1 file changed