Allow targets to custom legalize vector insertion and extraction.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217711 91177308-0d34-0410-b5e6-96231b3b80d8
[AArch64] Don't enable the post-RA MI scheduler at OptNone.

Hopefully, this will appease the bots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217712 91177308-0d34-0410-b5e6-96231b3b80d8
Stop suppress error messages in test case to see why one buildbot is failing

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217715 91177308-0d34-0410-b5e6-96231b3b80d8