*EXPERIMENTAL* build bzip2 which bz2 module is depending

Known problems:

* The patches was taken from Debian package and modified little bit.
  The pathch level should be configurable in `apply_patches`.
* The current impl builds binaries of bzip2 such like bzip2 and bunzip2.
  This must be the undesired behaviour.
set BZIP2_PATCH_STRIP=1 and reimported bzip2 patches from Debian package.
skip installing binaries of bzip2
set DYLD_LIBRARY_PATH in place of LD_LIBRARY_PATH on Darwin