genksyms: properly consider EXPORT_UNUSED_SYMBOL{,_GPL}()

Despite being unused these should also get a CRC calculated.
Primarily I view this as a consistency thing.  But I also think this is
one of the reasons why __crc_* need to be weak (which I think should be
avoided, and hence we should have the goal to eliminate this so that
failure to calculate a proper CRC for a symbol causes the build to fail).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Anibal Monsalve Salazar <anibal@debian.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>