Outdent labels as instructed in doc/hacking.txt.

Reported by Jonas Fonseca.

Also add an empty line above the label in init_tab; but there are
still several labels elsewhere that don't have empty lines above them.

src/terminal/event.c

@@ -424,7 +424,7 @@ handle_interlink_event(struct terminal *term, struct interlink_event *ilev)
 			break;
 		}
 
-	invalid_utf_8_start_byte:
+invalid_utf_8_start_byte:
 		term_send_ucs(term, UCS_REPLACEMENT_CHARACTER, modifier);
 		break;
 	}

src/terminal/tab.c

@@ -51,7 +51,8 @@ init_tab(struct terminal *term, void *data, window_handler_T handler)
 	 * above it if it were inactive, or below if it were active.  */
 	assert(term->main_menu == NULL);
 	pos = (struct window *) term->windows.prev;
- found_pos:
+
+found_pos:
 	add_at_pos(pos, win);
 
 	assert_window_stacking(term);