FS-3545 --resolve this is actually compliant when mixing ptimes in the same sdp…

FS-3545 --resolve this is actually compliant when mixing ptimes in the same sdp but since iLBC uses its own fmtp for ptime I will add this patch to make it beleive its 20 for the sake of arguement.  If you have any other problems with this, set the channel or global variable sdp_m_per_ptime=false to completely disable the default correct behaviour

src/mod/endpoints/mod_sofia/sofia_glue.c

@@ -583,6 +583,10 @@ void sofia_glue_set_local_sdp(private_object_t *tech_pvt, const char *ip, switch
 				
 				this_ptime = imp->microseconds_per_packet / 1000;
 				
+				if (!strcasecmp(imp->iananame, "ilbc")) {
+					this_ptime = 20;
+				}
+				
 				if (cur_ptime != this_ptime) {
 					char *bp = buf;
 					cur_ptime = this_ptime;