there is no multi_isa build support with armv8-a as the base micro architecture #1046

Output of 'strings libarm_compute.so | grep arm_compute_version':
arm_compute_version=v22.11 Build options: {'Werror': '1', 'debug': '0', 'neon': '1', 'opencl': '0', 'os': 'linux', 'openmp': '1', 'cppthreads': '0', 'arch': 'armv8.2-a', 'multi_isa': '1', 'build': 'native'} Git hash=b'1b3192e8a23513031163dc14d248f47671986121'

Platform: range of armv8 paltforms : Cortex-A72, Neoverse N1, Neoverse V1 etc...

Operating System: Ubuntu 20.04

Problem description:
multi_isa support mandated armv8.2-a as the base micro architecture, so today it's not possible to build a single ACL binary that covers all the armv8 architectures.

Workaround:
Here is the patch to lower the base architecture requirement to armv8-a for multi_isa builds. This covers all armv8-a platforms, however, excludes the FP16 kernels, which may be an acceptable tradeoff to get the broader armv8 support with single binary.

scons-mutli-isa-build-with-armv8-a-baseline.patch

Request:
The request is to provide multi_isa build armv8-a as base architecture, and support fp16 feature similar to bf16 and sve features supported today. Otherwise at least make armv8-a multi_isa without fp16 as the default build option and provide armv8.2-a based multi_isa as an option to get fp16 kernels.