kconfig: warn about overlong lines in help-texts

From busybox r22852.

package/config/lex.zconf.c_shipped

@@ -815,6 +815,11 @@ void new_string(void)
 void append_string(const char *str, int size)
 {
 	int new_size = text_size + size + 1;
+	if (size > 70) {
+		fprintf (stderr, "%s:%d warning: Overlong line\n",
+		current_file->name, current_file->lineno);
+	}
+
 	if (new_size > text_asize) {
 		new_size += START_STRSIZE - 1;
 		new_size &= -START_STRSIZE;

package/config/zconf.l

@@ -49,6 +49,10 @@ void new_string(void)
 void append_string(const char *str, int size)
 {
 	int new_size = text_size + size + 1;
+	if (size > 70) {
+	        fprintf (stderr, "%s:%d warning: Overlong line\n",
+			 current_file->name, current_file->lineno);
+	}
 	if (new_size > text_asize) {
 		new_size += START_STRSIZE - 1;
 		new_size &= -START_STRSIZE;