Add missing FALLTHROUGH comments to switch-case statements

This allows to suppress code analysis warnings in IDEs for missing break
statements.

src/db_upgrade.c

@@ -1664,11 +1664,15 @@ db_upgrade(sqlite3 *hdl, int db_ver)
       if (ret < 0)
 	return -1;
 
+      /* FALLTHROUGH */
+
     case 1901:
       ret = db_generic_upgrade(hdl, db_upgrade_v1902_queries, sizeof(db_upgrade_v1902_queries) / sizeof(db_upgrade_v1902_queries[0]));
       if (ret < 0)
 	return -1;
 
+      /* FALLTHROUGH */
+
     case 1902:
       ret = db_generic_upgrade(hdl, db_upgrade_v1903_queries, sizeof(db_upgrade_v1903_queries) / sizeof(db_upgrade_v1903_queries[0]));
       if (ret < 0)

src/misc.c

@@ -808,17 +808,17 @@ murmur_hash64(const void *key, int len, uint32_t seed)
   switch (len & 7)
     {
       case 7:
-	h ^= (uint64_t)(data_tail[6]) << 48;
+	h ^= (uint64_t)(data_tail[6]) << 48; /* FALLTHROUGH */
       case 6:
-	h ^= (uint64_t)(data_tail[5]) << 40;
+	h ^= (uint64_t)(data_tail[5]) << 40; /* FALLTHROUGH */
       case 5:
-	h ^= (uint64_t)(data_tail[4]) << 32;
+	h ^= (uint64_t)(data_tail[4]) << 32; /* FALLTHROUGH */
       case 4:
-	h ^= (uint64_t)(data_tail[3]) << 24;
+	h ^= (uint64_t)(data_tail[3]) << 24; /* FALLTHROUGH */
       case 3:
-	h ^= (uint64_t)(data_tail[2]) << 16;
+	h ^= (uint64_t)(data_tail[2]) << 16; /* FALLTHROUGH */
       case 2:
-	h ^= (uint64_t)(data_tail[1]) << 8;
+	h ^= (uint64_t)(data_tail[1]) << 8; /* FALLTHROUGH */
       case 1:
 	h ^= (uint64_t)(data_tail[0]);
 	h *= m;

src/outputs/cast.c

@@ -1471,6 +1471,8 @@ cast_session_shutdown(struct cast_session *cs, enum cast_state wanted_state)
 	if ((ret < 0) || (wanted_state >= CAST_STATE_MEDIA_LAUNCHED))
 	  break;
 
+	/* FALLTHROUGH */
+
       case CAST_STATE_MEDIA_LAUNCHED:
 	ret = cast_msg_send(cs, STOP, cast_cb_stop);
 	pending = 1;