[AArch64] Add command-line option predres

Prediction control instructions are only
mandatory from v8.5a onwards but is optional
from Armv8.0-A. This patch adds a command
line option to enable it by it's own.

Differential Revision: https://reviews.llvm.org/D56007


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350385 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed