use -mcpu=cortext-m4 for GD32F303

Author: mean

Platform/Initialization/DefaultCFlagsStm32.cmake

@@ -10,8 +10,13 @@ IF(NOT DEFINED ARDUINO_CFLAGS_SET)
     IF(NOT DEFINED MCU_SPEED )
         SET(MCU_SPEED 72000000L)
     ENDIF(NOT DEFINED MCU_SPEED )
-    
-    SET(ARDUINO_DEFAULT_CFLAGS " -ffunction-sections -fdata-sections -nostdlib --param max-inline-insns-single=500  -w   -mcpu=cortex-m3  -mthumb   -g ")
+
+    IF(DEFINED ARDUINO_MCU_FLAGS)   
+    ELSE(DEFINED ARDUINO_MCU_FLAGS)   
+        SET(ARDUINO_MCU_FLAGS "  -mcpu=cortex-m3")
+    ENDIF(DEFINED ARDUINO_MCU_FLAGS)   
+ 
+    SET(ARDUINO_DEFAULT_CFLAGS " -ffunction-sections -fdata-sections -nostdlib --param max-inline-insns-single=500  -w  ${ARDUINO_MCU_FLAGS}  -mthumb   -g ")
     SET(ARDUINO_DEFAULT_CFLAGS " ${ARDUINO_DEFAULT_CFLAGS}  -DGENERIC_BOOTLOADER -DF_CPU=${MCU_SPEED}L  -DARDUINO_ARCH_STM32F1 -DCONFIG_MAPLE_MINI_NO_DISABLE_DEBUG    ")
     #SET(ARDUINO_DEFAULT_CFLAGS " ${ARDUINO_DEFAULT_CFLAGS}  -DF_CPU=72000000L  -DARDUINO_ARCH_STM32F1 ")
 

select_mcu_stm32.cmake

@@ -17,6 +17,7 @@ ELSEIF(USE_GD32F303)
     SET(EXTENSION             "GD32F303")
     set(X_ARDUINO_DEFAULT_BOARD genericGD32F303C)        # Default Board ID, when not specified
     set(X_ARDUINO_CPU           GD32F303C8)
+    SET(ARDUINO_MCU_FLAGS               "  -mcpu=cortex-m4 ")
     ADD_DEFINITIONS("-DHIGH_SPEED_ADC")
     SET(X_ARDUINO_UPLOAD_METHOD BMP) # Use blackmagic link, if you comment it out you'll use DFU => 8kB flash
 ELSE()