The __builtin_ functions registered by aarch64_init_simd_builtins use signed
and/or unsigned types according to the qualifiers defined in aarch64-builtins.c
and used in aarch64-simd-builtins.def. These __builtin functions are then used
in arm_neon.h, with explicit casts converting between the signed/unsigned types
declared for the intrinsics and for the builtins.
These two patches add a few more sets of qualifiers, and use existing ones more
widely, allowing removing lots of the explicit casts from arm_neon.h.
There is no particular logic in the division between the two patches beyond that
the second patch uses sets of qualifiers defined in the first.
No regressions on aarch64-none-elf or aarch64_be-none-elf.
