We use an extended glob here, but were relying on having it globally set
in makepkg. This causes it to fail when used in scripts.
Since scripts using libmakepkg may not want extglob to be set, save and
restore the environment while explicitly setting extglob only where we
need it.
Signed-off-by: Levente Polyak <anthraxx@archlinux.org>
016fd2633e