Backport Ampere1B support to release/18.x

[ptomsich]

I would like to backport Ampere1B (-mcpu=ampere1b) support (#81297 , #81341, #81744) to the release/18.x branch.
These depend on PAUTH being correctly enabled by default for ARMv8.3-A+ (#78027); so that one needs to be backported to the release/18.x branch as well.

/cherry-pick a52eea6 fbba818 dd1897c 3369e34

[llvmbot]

@llvm/issue-subscribers-backend-aarch64

Author: Philipp Tomsich (ptomsich)

I would like to backport Ampere1B (-mcpu=ampere1b) support (#81297 , #81341, #81744) to the release/18.x branch. These depend on PAUTH being correctly enabled by default for ARMv8.3-A+ (#78027); so that one needs to be backported to the release/18.x branch as well.

/cherry-pick a52eea6 fbba818 dd1897c 3369e34

[llvmbot]

/pull-request #81857