sync: take pkgname/pkgver from stdin

[AladW]

From cd3a2e4:

Pass one to many arguments to check for newer versions existing in the AUR.
Each argument is assumed to be a package installed locally using B<pacman>(8).
If no arguments are given, pacman is queried for all foreign packages as an
input to this operation.

This rules out the case where an AUR package is in a (local) repository, but it is not installed on the host (e.g., for build servers). A possible alternative would be a stdin option for sync:

pacman -Qm | auracle sync - # classical case
pacman -Sl custom | awk '{print $2,$3}' | auracle sync - # local repo case

[falconindy]

What does reading from stdin offer over passing commandline args?

[AladW]

xargs is possible though it overwrites exit codes with its own in the 123-127 range (if there are plans to use different exit codes than 0/1). But other than that pacman -Sl ... | xargs auracle sync is fine provided uninstalled targets are not skipped.