x86: Show symbol name if insn decoder test failed

Show symbol name if insn decoder test find a difference.
This will help us to find out where the issue is.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
LKML-Reference: <20091116230624.5250.49813.stgit@harusame>
Signed-off-by: Ingo Molnar <mingo@elte.hu>