alpm_pkg_load() and parse_descfile() are specific to getting information
from package files, just as other code is specific to getting information
into or out of a package database. Move this code out of package.c, which
should eventually only contain operators on the pmpkg_t struct that do not
depend at all on where the data came from.
Signed-off-by: Dan McGee <dan@archlinux.org>