* New upstream stable release (80.0+build2)

[ Olivier Tilloy ]
* Re-enable and update debian/patches/unity-menubar.patch
* Fix build failure with Python 3.5
  - debian/patches/python3-remove-variable-annotations.patch

[ Rico Tzschichholz ]
* Update patches
  - debian/patches/armhf-reduce-linker-memory-use.patch
  - debian/patches/rust-drop-dll-checksums.patch
* Drop obsolete patches
  - debian/patches/revert-1fce91651f43.patch
* Drop custom icupkg command in favour of upstream buildsys handling
  - debian/build/rules.mk
  - debian/patches/use-system-icupkg.patch