This patch aims to reduce the include used by AArch64ISelLowering, allowing it
to be included by unittests so that they can reference the AArch64ISD nodes.
It:
- Moves the inclusion of AArch64SMEAttributes.h to the uses.
- Moves LowerPtrAuthGlobalAddressStatically to a static function, so that
AArch64PACKey is not required in the header.
- Moves the definitions of getExceptionPointerRegister to the cpp file, to
remove the reference of AArch64::X0.
8274be509e