[scons multi_isa] extend multi_isa build to support armv8-a march

This change adds support for multi isa build with armv8-a as the
base micro architecture. To enable this, use 'arch=armv8a' and 'multi_isa=1'
build flags during scons build. This build option doesn't include
fp16 vector arithmetic. To include fp16 vector arithmetic, use 'arch=armv8.2-a'
and 'multi_isa=1' build option.

Signed-off-by: Sunita Nadampalli <nadampal@amazon.com>
Change-Id: Ib5ca61dc65603382baee53b3ec30b2b817beda3c
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/9474
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: SiCong Li <sicong.li@arm.com>
Reviewed-by: Viet-Hoa Do <viet-hoa.do@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>
diff --git a/SConscript b/SConscript
index 7ea59d2..c774a55 100644
--- a/SConscript
+++ b/SConscript
@@ -94,8 +94,12 @@
                            'ARM_COMPUTE_ENABLE_I8MM', 'ARM_COMPUTE_ENABLE_SVEF32MM'])
 
     # Build all the common files for the base architecture
-    lib_static_objs += build_obj_list(filedefs["armv8.2-a"], lib_files, static=True)
-    lib_shared_objs += build_obj_list(filedefs["armv8.2-a"], lib_files, static=False)
+    if env['arch'] == 'armv8a':
+        lib_static_objs += build_obj_list(filedefs["armv8-a"], lib_files, static=True)
+        lib_shared_objs += build_obj_list(filedefs["armv8-a"], lib_files, static=False)
+    else:
+        lib_static_objs += build_obj_list(filedefs["armv8.2-a"], lib_files, static=True)
+        lib_shared_objs += build_obj_list(filedefs["armv8.2-a"], lib_files, static=False)
 
     # Build the SVE specific files
     lib_static_objs += build_obj_list(filedefs["armv8.2-a-sve"], lib_files_sve, static=True)