build: GCC 5.1.x catches some new const, array bounds and missing paren issues

Fixed 1 issue in each of the affected files.

ASTERISK-25494 #close
Reported-by: George Joseph
Tested-by: George Joseph

Change-Id: I818f149cd66a93b062df421e1c73c7942f5a4a77

channels/chan_dahdi.c

@@ -18618,6 +18618,11 @@ static int process_dahdi(struct dahdi_chan_conf *confp, const char *cat, struct
 					cadence_is_ok = 0;
 				}
 
+				/* This check is only needed to satisfy the compiler that element_count can't cause an out of bounds */
+				if (element_count >= ARRAY_LEN(c)) {
+					element_count = ARRAY_LEN(c) - 1;
+				}
+
 				/* Ring cadences cannot be negative */
 				for (i = 0; i < element_count; i++) {
 					if (c[i] == 0) {

channels/chan_skinny.c

@@ -4379,7 +4379,7 @@ static int skinny_call(struct ast_channel *ast, const char *dest, int timeout)
 
 	AST_LIST_TRAVERSE(ast_channel_varshead(ast), current, entries) {
 		if (!(strcasecmp(ast_var_name(current),"SKINNY_AUTOANSWER"))) {
-			if (d->hookstate == SKINNY_ONHOOK && !sub->aa_sched < 0) {
+			if (d->hookstate == SKINNY_ONHOOK && !(sub->aa_sched < 0)) {
 				char buf[24];
 				int aatime;
 				char *stringp = buf, *curstr;

channels/sig_pri.c

@@ -4500,7 +4500,7 @@ static void sig_pri_handle_subcmds(struct sig_pri_span *pri, int chanpos, int ev
 					f.frametype = AST_FRAME_TEXT;
 					f.subclass.integer = 0;
 					f.offset = 0;
-					f.data.ptr = &subcmd->u.display.text;
+					f.data.ptr = (void *)&subcmd->u.display.text;
 					f.datalen = subcmd->u.display.length + 1;
 					ast_queue_frame(owner, &f);
 					ast_channel_unlock(owner);