[llvm-mca][UpdateTestChecks] Don't try to align blocks that have already been subject to alignment in update_mca_test_checks.py

This fixes PR39466.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345499 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed