~mozillateam/firefox/firefox-beta.trusty

* New upstream release from the beta channel (FIREFOX_67_0b5_BUILD1)
* Update patches
  - debian/patches/partially-revert-google-search-update.patch
  - debian/patches/mark-distribution-search-engines-as-read-only.patch
  - debian/patches/support-coinstallable-trunk-build.patch
  - debian/patches/cleanup-old-distribution-search-engines.patch
  - debian/patches/ubuntu-ua-string-changes.patch
  - debian/patches/armhf-disable-unaligned-fp-access-emulation.patch
* Bump build-dep on rustc >= 1.32.0 and cargo >= 0.33
* Update cbindgen to 0.8.2
  - debian/build/create-tarball.py