multiple targets per invocation

[mmirate]

In case of a power loss during a pacman -Syu - and in case some shared library pacman needs didn't get wiped off the disk - it is useful to run something like lostfiles to find all of the files whose ownership is no longer in the package database, and run pkgfile on each such file to determine the list of packages to reinstall. However, pkgfile has an inevitable and significant per-invocation overhead. Efficiency would be much improved if the user could supply many "target" arguments to pkgfile and then expect a (deduplicated?) list of any packages which are supposed to supply any of the named targets, without regard for any targets which are not in the pkgfile database; because pkgfile could respond to such an invocation by searching for all of the requested files in a single scan of its database.