test-release.sh: Perform the sed substitution on both files (PR42739)

test-release.sh: Perform the sed substitution on both files (PR42739)

The comparison would otherwise fail if Phase2 occurrs naturally in the
object file. It would get replaced with Phase3 in the one .o, but not
in the other.

We were already running both files through sed to have them processed in
this same way; this is a logical extension of that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@367847 91177308-0d34-0410-b5e6-96231b3b80d8