gcc: fix sparcv8 compile issue

Fix compile issue with gcc 7.1.0:
/tmp/ccxalnSf.s: Assembler messages:
/tmp/ccxalnSf.s:12: Error: Architecture mismatch on "rd %tick,%o1".
/tmp/ccxalnSf.s:12: (Requires v9|v9a|v9b|v9c|v9d|v9e|v9v|v9m|m8; requested architecture is v8.)
/tmp/ccxalnSf.s:13: Error: Architecture mismatch on "srlx %o1,32,%o0".
/tmp/ccxalnSf.s:13: (Requires v9|v9a|v9b|v9c|v9d|v9e|v9v|v9m|m8; requested architecture is v8.)
/tmp/ccxalnSf.s:30: Error: Architecture mismatch on "rd %ccr,%g0".
/tmp/ccxalnSf.s:30: (Requires v9|v9a|v9b|v9c|v9d|v9e|v9v|v9m|m8; requested architecture is v8.)
/tmp/ccxalnSf.s:33: Error: Architecture mismatch on "rd %ccr,%g0".
/tmp/ccxalnSf.s:33: (Requires v9|v9a|v9b|v9c|v9d|v9e|v9v|v9m|m8; requested architecture is v8.)
/tmp/ccxalnSf.s:36: Error: Architecture mismatch on "rd %ccr,%g0".
/tmp/ccxalnSf.s:36: (Requires v9|v9a|v9b|v9c|v9d|v9e|v9v|v9m|m8; requested architecture is v8.)
/tmp/ccxalnSf.s:39: Error: Architecture mismatch on "rd %ccr,%g0".
/tmp/ccxalnSf.s:39: (Requires v9|v9a|v9b|v9c|v9d|v9e|v9v|v9m|m8; requested architecture is v8.)
Makefile:684: recipe for target 'os-unix-sysdep.lo' failed

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>