bugfix for art-net transmit

art-net transmit was not sending out LEDs, but only transmitted headers repeatedly (thanks @troyhacks for noticing).

Actually such problems can be found by newer compilers, so i've added the warning option to [esp32_idf_V4].

wled00/udp.cpp: In function 'uint8_t realtimeBroadcast(uint8_t, IPAddress, uint16_t, uint8_t*, uint8_t, bool)':
wled00/udp.cpp:824:40: warning: declaration of 'byte buffer [12]' shadows a parameter [-Wshadow=compatible-local]
         byte buffer[ART_NET_HEADER_SIZE];
                                        ^
wled00/udp.cpp:720:85: note: shadowed declaration is here
 uint8_t realtimeBroadcast(uint8_t type, IPAddress client, uint16_t length, uint8_t *buffer, uint8_t bri, bool isRGBW)  {

platformio.ini

@@ -247,6 +247,7 @@ lib_deps =
 platform = espressif32@5.2.0
 platform_packages =
 build_flags = -g
+  -Wshadow=compatible-local ;; emit warning in case a local variable "shadows" another local one
   -DARDUINO_ARCH_ESP32 -DESP32
   #-DCONFIG_LITTLEFS_FOR_IDF_3_2
   -D CONFIG_ASYNC_TCP_USE_WDT=0

wled00/udp.cpp

@@ -821,9 +821,9 @@ uint8_t realtimeBroadcast(uint8_t type, IPAddress client, uint16_t length, uint8
           }
         }
 
-        byte buffer[ART_NET_HEADER_SIZE];
-        memcpy_P(buffer, ART_NET_HEADER, ART_NET_HEADER_SIZE);
-        ddpUdp.write(buffer, ART_NET_HEADER_SIZE); // This doesn't change. Hard coded ID, OpCode, and protocol version.
+        byte header_buffer[ART_NET_HEADER_SIZE];
+        memcpy_P(header_buffer, ART_NET_HEADER, ART_NET_HEADER_SIZE);
+        ddpUdp.write(header_buffer, ART_NET_HEADER_SIZE); // This doesn't change. Hard coded ID, OpCode, and protocol version.
         ddpUdp.write(sequenceNumber & 0xFF); // sequence number. 1..255
         ddpUdp.write(0x00); // physical - more an FYI, not really used for anything. 0..3
         ddpUdp.write((currentPacket) & 0xFF); // Universe LSB. 1 full packet == 1 full universe, so just use current packet number.