[ARM/AArch64][v8.5A] Add Armv8.5-A target

This patch allows targeting Armv8.5-A, adding the architecture to
tablegen and setting the options to be identical to Armv8.4-A for the
time being. Subsequent patches will add support for the different
features included in the Armv8.5-A Reference Manual.

Patch by Pablo Barrio!

Differential revision: https://reviews.llvm.org/D52470



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343102 91177308-0d34-0410-b5e6-96231b3b80d8
14 files changed