This patch adds support for dynamic R_AARCH64_AUTH_* relocations
(including RELR compressed AUTH relocations) as described here:
https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst#auth-variant-dynamic-relocations
Co-authored-by: Peter Collingbourne <peter@pcc.me.uk>