[ThinLTO] Make test for promoted names more specific

With r314527, promoted values get a suffix that is a decimal value of
the module hash instead of hex. Change the regex to match only decimal
suffix values.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316544 91177308-0d34-0410-b5e6-96231b3b80d8