fix: various errors in implementation of BTI

Amend call type in refmvs. Because these blocks are reached via
blr x11, they need to be annotated.

Add missing BTI landing pads in ipred.S and ipred16.S. Because the
subroutines are called via a br from register, they need annotation with
'bti j' (AARCH64_VALID_JUMP_TARGET).