🩹 Restore usleep for native / sim

Author: thinkyhead

Marlin/src/HAL/NATIVE_SIM/u8g/LCD_defines.h

@@ -25,6 +25,8 @@
  * Native/Simulator LCD-specific defines
  */
 
+void usleep(uint64_t microsec);
+
 uint8_t u8g_com_sw_spi_fn(u8g_t *u8g, uint8_t msg, uint8_t arg_val, void *arg_ptr);
 uint8_t u8g_com_ST7920_sw_spi_fn(u8g_t *u8g, uint8_t msg, uint8_t arg_val, void *arg_ptr);