There's no API functions exposed which allow manipulation of this type,
so remove it from public view. Also, rename the public and private
alpm_db_get_pkgcache symbol to alpm_db_get_pkgcache_has.

Signed-off-by: Dave Reisner <d@falconindy.com>
Signed-off-by: Dan McGee <dan@archlinux.org>