scripts/make-repo: Set CARCH before sourcing packages during dependency installation.

This fixes recstudio and jd-gui, which have conditional dependencies.
Example:

    [[ $CARCH == x86_64 ]] && depends=('lib32-gtk2')
scripts/find-package: Add archpwn.
merge-real: Fix double architecture support.
sign-real and make-real: Add 'archs' variable.
sign: Make the output more useful.
Increment pkgrel in a few package.