configure.ac: Introduce HAVE_ARM_ASM/HAVE_AARCH64_ASM and the -D flags.
I've been trying to get away without these conditionals in vc4's NEON code, but it meant compiling extra unused code on x86, and build failing on ARMv6. v2: Use the _arm/_arm64 flags to simplify detection (suggested by Rob), but hide the _arm version under ARCH_ARM_HAVE_NEON to keep from trying to build this stuff for armv5te. Tested-by:Rob Herring <robh@kernel.org> Reviewed-by:
Matt Turner <mattst88@gmail.com> (cherry picked from commit ba8533b6)