Created by: c-rhodes
This commit implements codegen_aflags_clobber on aarch64, using the msr instruction to set the NZCV system register. This will also be used by the inline.dll.c tests, once the NZCV flags are restored there.
The x86 implementation of codegen_aflags_clobber has also been moved to cleancall-opt-shared.h.
Issue: #2796