gdb/copyright.py: run autoconf

The last new year procedure missed running autoreconf in gnulib/ and
sim/ to update the Makefile.in files (following the updates of the
corresponding Makefile.am files).  I propose to make the script run
`autoreconf -v` to ensure we don't miss those anymore.  It takes a bit
of time, but that script isn't run very frequently (I'd say more or less
once a year).

Change-Id: Iab64415cedac716632d6a1230ebb87cc3190f4e4
Approved-By: Tom Tromey <tom@tromey.com>