__attribute__ does not need to be treated as a variadic macro, since

it is always used as __attribute__((...)).  Since variadic macros seem
to confuse poor doxygen, change it to a single-valued macro.

src/include/compiler.h

@@ -7,7 +7,7 @@
  *
  */
 #ifdef DOXYGEN
-#define __attribute__(...)
+#define __attribute__(x)
 #endif
 
 /*