bzip2: improve symlink creation

bzip2: improve symlink creation

This recipe inherits relative_symlinks as otherwise ${bindir}/bunzip2 is
an absolute link to ${bindir}/bzip2.  However, we drop the Makfile.am
into the tree so instead of working around the problem, we can just fix
the Makefile rules directly.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>