[llvm-symbolizer] Minor typedef cleanup. NFC.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219682 91177308-0d34-0410-b5e6-96231b3b80d8
[AArch64] Fix crash with empty/pseudo-only blocks in A53 erratum (835769) workaround

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219684 91177308-0d34-0410-b5e6-96231b3b80d8