res_rtp_asterisk: Crash if no candidates received for component

When starting ice if there is not at least one remote ice candidate with an RTP
component asterisk will crash. This is due to an assertion in pjnath as it
expects at least one candidate with an RTP component. Added a check to make
sure at least one candidate contains an RTP component and at least one candidate
has an RTCP component.

ASTERISK-24383 #close
Review: https://reviewboard.asterisk.org/r/4039/
........

Merged revisions 425029 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@425030 f38db490-d61c-443f-a65b-d21fe96a405b