aarch64: Define out-of-class static constants

aarch64: Define out-of-class static constants

While reworking the aarch64 feature descriptions, I forgot
to add out-of-class definitions of some static constants.
This could lead to a build failure with some compilers.

This was seen with some WIP to increase the number of extensions
beyond 64.  It's latent on trunk though, and a regression from
before the rework.

gcc/
	* config/aarch64/aarch64-feature-deps.h (feature_deps::info): Add
	out-of-class definitions of static constants.