Add "autoframing" option to sip.conf.sample and h323.conf.sample.

The autoframing option was added to chan_sip.c in r43243 (mogorman,
2006-09-19 01:32:57), but never made its way into the sample configs.

Review: https://reviewboard.asterisk.org/r/2768/


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/1.8@396994 f38db490-d61c-443f-a65b-d21fe96a405b