pjsip: Increase maximum packet size.

The maximum packet size for PJSIP has been increased to handle the
multiple streams being added for WebRTC.

Change-Id: I9ea1e8d02668c544acadcb1c6200e1cc1bd588b3

third-party/pjproject/patches/config_site.h

@@ -68,7 +68,7 @@
   Enabling it will result in SEGFAULTS when URIs containing escape sequences are encountered.
 */
 #undef PJSIP_UNESCAPE_IN_PLACE
-#define PJSIP_MAX_PKT_LEN			6000
+#define PJSIP_MAX_PKT_LEN			32000
 
 #undef PJ_TODO
 #define PJ_TODO(x)