Depends on #120010
`TLSDESC_AUTH_CALLSEQ` pseudo-instruction is introduced which is later expanded
to actual instruction sequence like the following.
```
adrp x0, :tlsdesc_auth:var
ldr x16, [x0, #:tlsdesc_auth_lo12:var]
add x0, x0, #:tlsdesc_auth_lo12:var
blraa x16, x0
(TPIDR_EL0 offset now in x0)
```
Only SelectionDAG ISel is supported.
Tests starting with 'ptrauth-' have corresponding variants w/o this prefix.
52bbe20eb4