res_pjsip.c: Fix crash from corrupt saved SUBSCRIBE message.

If the saved SUBSCRIBE message is not parseable for whatever reason then
Asterisk could crash when libpjsip tries to parse the message and adds an
error message to the parse error list.

* Made ast_sip_create_rdata() initialize the parse error rdata list.  The
list is checked after parsing to see that it remains empty for the
function to return successful.

ASTERISK-25306
Reported by Mark Michelson

Change-Id: Ie0677f69f707503b1a37df18723bd59418085256