The first three patches are trivial changes to the feature list to reflect recent changes in the ACLE. Patch 4 removes most of the FMV multiversioning features that don't work at the moment, and should be entirely uncontroversial.
Patch 5 handles the remaining cases, where there's an inconsistency in how features are named in the current FMV specification compared to the existing command line options. It might be better to instead preserve the "memtag2", "ssbs2" and "ls64_accdata" names for now; I'd be happy to commit either version. Bootstrapped and regression tested on aarch64. Ok for master?
