tm: updated the reason text for canceled branches after one is answered

- change answered elsewhere to call completed elsewhere
- "Call completed elsewhere", RFC3326, defines this as the string to send
- submited by William King <william.king@quentustech.com>, GH #610

(cherry picked from commit e75837a)

modules/tm/t_cancel.c

@@ -43,7 +43,7 @@ typedef struct cancel_reason_map {
 } cancel_reason_map_t;
 
 static cancel_reason_map_t _cancel_reason_map[] = {
-	{ 200, str_init("Answered elsewhere") },
+	{ 200, str_init("Call completed elsewhere") },
 	{ 0, {0, 0} }
 };