Notes on the SCFI testsuite in GAS:

* At this time, SCFI machinery is only supported for x86_64 and aarch64.

* When adding more core SCFI tests (scfi-* tests), please keep CFI
  annotations updated in the .s files.  Ideally the test should be run with and
  without --scfi (as is done currently for the core SCFI tests); Such workflow
  ensures sanity checking of the CFI annotations.

* Note that GAS issues a warning:
    "Warning: SCFI ignores most user-specified CFI directives"
  when it encounters CFI directives in the input assembly and SCFI is enabled.
  To bypass the noise from this warning, while keeping the testcases
  useful/understandable, most of the SCFI core tests are run twice. E.g.,
     - run_dump_test "scfi-cfi-add-1" // ignores warnings
     - run_list_test "scfi-cfi-add-1" "--scfi=experimental --warn" // tests warnings

* Tests named ginsn-* generally aim to ensure graceful ginsn creation process for
  various instructions.
