Better fallthrough annotation macro.

src/cdrom/cdrom_image_backend.c

@@ -652,9 +652,7 @@ cdi_cue_get_buffer(char *str, char **line, int up)
                     done = 1;
                     break;
                 }
-#ifdef FALLTHROUGH_ANNOTATION
-                [[fallthrough]];
-#endif
+                fallthrough;
 
             default:
                 if (up && islower((int) *s))

src/cdrom/cdrom_mitsumi.c

@@ -324,9 +324,7 @@ mitsumi_cdrom_out(uint16_t port, uint8_t val, void *priv)
                                 break;
                             case 5:
                                 dev->readmsf = 0;
-#ifdef FALLTHROUGH_ANNOTATION
-                                [[fallthrough]];
-#endif
+                                fallthrough;
                             case 4:
                             case 3:
                                 dev->readmsf |= CD_DCB(val) << ((dev->cmdrd_count - 3) << 3);