Correctly re-process non-option cmdline args on sighup

Whenever we had an non-option commandline arguments *and*
option-bearing commandline arguments on the commandline, we would save
only the latter across invocations of options_init_from_torrc, but
take their existence as license not to re-parse the former.  Yuck!

Incidentally, this fix lets us throw away the backup_arg[gv] logic.

Fix for bug 9746; bugfix on d98dfb3746790448b0dcff2aa9a00e5e2602688a,
not in any released Tor.  Found by Damian. Thanks, Damian!