MFC r351329:
gprof: disable building of a.out components On arm64, riscv, and s390x disable building of aout components. This allows gprof to build on these architectures which never supported the legacy a.out binary format.
Note: there might be more work needed for arm64 or risv and the MACHINE_
checks are based on what was use elsewhere in the tree at that time. Other
will fix these parts with follow-up work.