add ccdlflags for show_bzversion

esp. to add -rpath linker settings on solaris or elsewhere,
where bzip2 is installed in a non-standard location.
RT #68572
Thanks to leont for the suggestion.
[cpan #68572] ccdlflags and constant => 1.04

add ccdlflags to show_bzversion for the missing -R also.
require constant 1.04 (since 5.8) to accept hashrefs.
2.18: add META to MANIFEST