Fixed bug: don't add SDP media ptime parameter if ilbc is not offered.

git-svn-id: http://yate.null.ro/svn/yate/trunk@5510 acf43c95-373e-0410-b603-e72c3f656dc1
Merge remote-tracking branch 'trunk' into upstream
Merge branch 'upstream' of github.com:vir/yate into deb
Updated debian package version to 4.3.1~svn5510