Optimize set.matched().

Take advantage of the fact that the array of indexes returned from
the vre2 call is now sorted (but still using a linear search).

src/vmod_re2.c

@@ -768,6 +768,7 @@ VCL_BOOL
 vmod_set_matched(VRT_CTX, struct vmod_re2_set *set, VCL_INT n)
 {
 	struct task_set_match *task;
+	unsigned i;
 
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
 	CHECK_OBJ_NOTNULL(set, VMOD_RE2_SET_MAGIC);
@@ -788,10 +789,9 @@ vmod_set_matched(VRT_CTX, struct vmod_re2_set *set, VCL_INT n)
 	WS_Assert_Allocated(ctx->ws, task->matches,
 			    task->nmatches * sizeof(int));
 	n--;
-	for (unsigned i = 0; i < task->nmatches; i++)
-		if (task->matches[i] == n)
-			return 1;
-	return 0;
+	for (i = 0; i < task->nmatches && task->matches[i] < n; i++)
+		;
+	return task->matches[i] == n;
 }
 
 VCL_INT