[std C compliance] replace #pragma once in common.h with standard #ifndef guard

common.h

@@ -1,5 +1,7 @@
-#pragma once
+#ifndef COMMONH
-
     typedef unsigned char byte; //8bit (byte) variable type
     typedef unsigned short word; //16bit (2byte) variable type
     typedef enum {false, true} bool;
+#endif
+
+#define COMMONH