x86: Add {load}/{store} tests for apx instructions.
gas/ChangeLog:
* testsuite/gas/i386/x86-64.exp: Add {load}/{store} tests for apx
instructions.
* testsuite/gas/i386/x86-64-pseudos-apx.d: New test.
* testsuite/gas/i386/x86-64-pseudos-apx.s: Ditto.