the bzip2 patch is pretty extensive, so here's a brief explanation.

1. the first part just sets the correct environmental variable values for a
   static build that gets installed to / instead of /usr/local.

2. most of the other changes consist of replacing $(PREFIX)/man with
   $(PREFIX)/share/man.  without these changes, bzip2 creates a /man directory
   and installs the manpages there instead of in /share/man like every other
   package.

3. in the recommended alpine linux bootstrap host, copying over a symlink to
   busybox doesn't replace the symlink.  instead it replaces the busybox binary!
   so changes were added to remove possible symlinks before copying "over" them.