bzip2

Not released very frequently. In addition to the general steps, we patch the source to add a custom CMake build (packages/bzip2/patches/cmake.diff) which requires updating:

• update the release version and shared library version in CMakeLists.txt
• check that the source file list in CMakeLists.txt is up to date (a diff of the old and new bzip2 sources will show the changes in the upstream build files)