meson: fix build on arm64
Would fail like:
Checking if "compiler supports ARMv7/AArch64 NEON intrinsics" : links: NO
Checking if "compiler supports ARMv7/AArch64 NEON intrinsics with -mfpu=neon" : links: YES
Checking if "compiler supports AArch64 NEON intrinsics" : links: NO
Checking if "compiler supports AArch64 NEON intrinsics with -mfpu=neon" : links: NO
Message: Compiler does not support AArch64 NEON intrinsics
../silk/meson.build:28:45: ERROR: Unknown variable "have_arm_intrinsics_or_asm".
since commit 08088411.
Draft for now, needs more testing. This is ready now.
Edited by Tim-Philipp Müller