llvm-link: Factor out loop over input files, NFC

Factor the loop for linking input files together into a combined module
into a separate function.  This is in preparation for an upcoming patch
that runs the logic twice.

Patch by Luqman Aden!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235472 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed