Removed temporary diagnostic to determine gcc version on Solaris

Removed temporary diagnostic to determine gcc version on Solaris
buildbot host.  It's 4.5.2.  4.6.0 and later return an error
status with an unrecognized option, which we rely on for the test
for -Qunused-arguments.  4.5.2 doesn't.  But that option doesn't
produce any errors, just warnings that don't contain "warning".
So ignore it.