tweak the v21 detector to detect an additional pattern of hits and misses

........

Merged revisions 342605 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@342606 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/dsp.c

@@ -631,7 +631,7 @@ static int v21_detect(struct ast_dsp *dsp, v21_detect_state_t *s, int16_t *amp,
 		}
 
 		if (hit) {
-			if (s->miss_count == 3) {
+			if (s->miss_count == 3 || (s->hit_count == 1 && s->miss_count == 2)) {
 				s->hit_count++;
 			} else {
 				s->hit_count = 1;