HAL include and other adjustments (#14525)

Marlin/src/HAL/HAL_AVR/HAL.h

@@ -22,8 +22,6 @@
 // Includes
 // --------------------------------------------------------------------------
 
-#include <stdint.h>
-
 #include "../shared/Marduino.h"
 #include "../shared/HAL_SPI.h"
 #include "fastio_AVR.h"
@@ -33,9 +31,11 @@
 #ifdef USBCON
   #include "HardwareSerial.h"
 #else
+  #define HardwareSerial_h // Hack to prevent HardwareSerial.h header inclusion
   #include "MarlinSerial.h"
 #endif
 
+#include <stdint.h>
 #include <util/delay.h>
 #include <avr/eeprom.h>
 #include <avr/pgmspace.h>

Marlin/src/HAL/HAL_AVR/MarlinSerial.h

@@ -275,7 +275,6 @@
 
 #endif // !USBCON
 
-
 #ifdef INTERNAL_SERIAL_PORT
   template <uint8_t serial>
   struct MarlinInternalSerialCfg {

Marlin/src/HAL/HAL_AVR/endstop_interrupts.h

@@ -36,7 +36,6 @@
  * (Located in Marlin/buildroot/share/pin_interrupt_test/pin_interrupt_test.ino)
  */
 
-#include "../../core/macros.h"
 #include "../../module/endstops.h"
 
 #include <stdint.h>