asterisk: two denial of service flaws

From the Fedora advisory:

CVE-2012-3863: If Asterisk sends a re-invite and an endpoint responds to the re-invite with a provisional response but never sends a final response, then the SIP dialog structure is never freed and the RTP ports for the call are never released. If an attacker has the ability to place a call, they could create a denial of service by using all available RTP ports.

CVE-2012-3812: If a single voicemail account is manipulated by two parties simultaneously, a condition can occur where memory is freed twice causing a crash.