Better fallthrough annotation macro.

src/scsi/scsi_buslogic.c

@@ -1232,9 +1232,7 @@ BuslogicPCIWrite(UNUSED(int func), int addr, uint8_t val, void *priv)
         case 0x10:
             val &= 0xe0;
             val |= 1;
-#ifdef FALLTHROUGH_ANNOTATION
-            [[fallthrough]];
-#endif
+            fallthrough;
 
         case 0x11:
         case 0x12:
@@ -1258,9 +1256,7 @@ BuslogicPCIWrite(UNUSED(int func), int addr, uint8_t val, void *priv)
 
         case 0x14:
             val &= 0xe0;
-#ifdef FALLTHROUGH_ANNOTATION
-            [[fallthrough]];
-#endif
+            fallthrough;
 
         case 0x15:
         case 0x16:

src/scsi/scsi_cdrom.c

@@ -883,9 +883,7 @@ scsi_cdrom_update_request_length(scsi_cdrom_t *dev, int len, int block_len)
                     break;
                 }
             }
-#ifdef FALLTHROUGH_ANNOTATION
-            [[fallthrough]];
-#endif
+            fallthrough;
 
         default:
             dev->packet_len = len;
@@ -961,9 +959,7 @@ scsi_cdrom_command_common(scsi_cdrom_t *dev)
                 scsi_cdrom_log("CD-ROM %i: Seek period: %" PRIu64 " us\n",
                                dev->id, (uint64_t) period);
                 dev->callback += period;
-#ifdef FALLTHROUGH_ANNOTATION
-                [[fallthrough]];
-#endif
+                fallthrough;
             case 0x25:
             case 0x42:
             case 0x43:
@@ -1940,9 +1936,7 @@ begin:
             /* IMPORTANT: Convert the command to new read CD
                           for pass through purposes. */
             dev->current_cdb[0] = GPCMD_READ_CD;
-#ifdef FALLTHROUGH_ANNOTATION
-            [[fallthrough]];
-#endif
+            fallthrough;
 
         case GPCMD_READ_6:
         case GPCMD_READ_10:

src/scsi/scsi_disk.c

@@ -597,9 +597,7 @@ scsi_disk_command(scsi_common_t *sc, uint8_t *cdb)
                 scsi_disk_invalid_field(dev);
                 return;
             }
-#ifdef FALLTHROUGH_ANNOTATION
-            [[fallthrough]];
-#endif
+            fallthrough;
         case GPCMD_SCSI_RESERVE:
         case GPCMD_SCSI_RELEASE:
         case GPCMD_TEST_UNIT_READY:

src/scsi/scsi_pcscsi.c

@@ -1030,9 +1030,7 @@ esp_reg_write(esp_t *dev, uint32_t saddr, uint32_t val)
     switch (saddr) {
         case ESP_TCHI:
             dev->tchi_written = 1;
-#ifdef FALLTHROUGH_ANNOTATION
-            [[fallthrough]];
-#endif
+            fallthrough;
         case ESP_TCLO:
         case ESP_TCMID:
             esp_log("Transfer count regs %02x = %i\n", saddr, val);

src/scsi/scsi_x54x.c

@@ -490,9 +490,7 @@ x54x_bios_command(x54x_t *x54x, uint8_t max_id, BIOSCMD *cmd, int8_t islba)
 
             default:
                 x54x_log("BIOS: Unimplemented command: %02X\n", cmd->command);
-#ifdef FALLTHROUGH_ANNOTATION
-                [[fallthrough]];
-#endif
+                fallthrough;
             case 0x05: /* Format Track, invalid since SCSI has no tracks */
             case 0x0a: /* ???? */
             case 0x0b: /* ???? */