Merge pull request zephyrproject-rtos#139 from KurtE/pure_analog_cpp_only

Fix .c file compile that include <Arduino.h>

Author: facchinm

variants/arduino_giga_r1_stm32h747xx_m7/pure_analog_pins.h

@@ -1,5 +1,6 @@
 #ifndef _PURE_ANALOG_PINS_
 #define _PURE_ANALOG_PINS_
+#ifdef __cplusplus
 
 /******************************************************************************
  * INCLUDE
@@ -54,4 +55,6 @@ void      PURE_ANALOG_AS_DIGITAL_ATTRIBUTE analogWrite (PureAnalogPin pin, int v
 
 #undef PURE_ANALOG_AS_DIGITAL_ATTRIBUTE
 
+#endif /* __cplusplus */
+
 #endif /* _PURE_ANALOG_PINS_ */

variants/arduino_portenta_h7_stm32h747xx_m7/pure_analog_pins.h

@@ -5,6 +5,7 @@
  */
 #ifndef _PURE_ANALOG_PINS_
 #define _PURE_ANALOG_PINS_
+#ifdef __cplusplus
 
 /******************************************************************************
  * INCLUDE
@@ -59,4 +60,6 @@ void      PURE_ANALOG_AS_DIGITAL_ATTRIBUTE analogWrite (PureAnalogPin pin, int v
 
 #undef PURE_ANALOG_AS_DIGITAL_ATTRIBUTE
 
+#endif /* __cplusplus */
+
 #endif /* _PURE_ANALOG_PINS_ */