codecs: Add support for WebRTC iLBC 2.0.

When the latest version of that library was installed, Asterisk did not build.

ASTERISK-27669
Reported by: Николай Михо

Change-Id: I27e09bb875fdd56423bd9fae1be85fddb428eb96

codecs/codec_ilbc.c

@@ -42,8 +42,8 @@
 
 #ifdef ILBC_WEBRTC
 #include <ilbc.h>
-typedef WebRtc_UWord16 ilbc_bytes;
-typedef WebRtc_Word16  ilbc_block;
+typedef uint16_t ilbc_bytes;
+typedef int16_t  ilbc_block;
 #define BUF_TYPE i16
 #else
 #include "ilbc/iLBC_encode.h"