Add extension that enables 32-bit compat vDSO for arm64 kernels.
Without vDSO, 32-bit applications using gettimeofday() syscall heavily
suffer significant performance penalty on arm64 systems.
The extension:
- Adds gcc-arm-linux-gnueabi as build dependency
- Sets CROSS_COMPILE_COMPAT for kernel make
- Enables CONFIG_COMPAT_VDSO in kernel config
Enable with: ENABLE_EXTENSIONS=arm64-compat-vdso
Refs: https://github.com/armbian/build/issues/9216
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
