AP_HAL: prevent some FastDelegate warnings

libraries/AP_HAL/utility/FastDelegate.h

@@ -176,7 +176,7 @@ inline OutputClass horrible_cast(const InputClass input){
 	// If the compile fails here, it means the compiler has peculiar
 	// unions which would prevent the cast from working.
 	typedef int ERROR_CantUseHorrible_cast[sizeof(InputClass)==sizeof(u) 
-		&& sizeof(InputClass)==sizeof(OutputClass) ? 1 : -1];
+                                               && sizeof(InputClass)==sizeof(OutputClass) ? 1 : -1] __attribute((unused));
 	u.in = input;
 	return u.out;
 }
@@ -292,7 +292,7 @@ struct SimplifyMemFunc {
 		GenericMemFuncType &bound_func) { 
 		// Unsupported member function type -- force a compile failure.
 	    // (it's illegal to have a array with negative size).
-		typedef char ERROR_Unsupported_member_function_pointer_on_this_compiler[N-100];
+		typedef char ERROR_Unsupported_member_function_pointer_on_this_compiler[N-100] __attribute((unused));
 		return 0; 
 	}
 };
@@ -778,7 +778,7 @@ public:
 		// Ensure that there's a compilation failure if function pointers 
 		// and data pointers have different sizes.
 		// If you get this error, you need to #undef FASTDELEGATE_USESTATICFUNCTIONHACK.
-		typedef int ERROR_CantUseEvilMethod[sizeof(GenericClass *)==sizeof(function_to_bind) ? 1 : -1];
+		typedef int ERROR_CantUseEvilMethod[sizeof(GenericClass *)==sizeof(function_to_bind) ? 1 : -1] __attribute((unused));
 		m_pthis = horrible_cast<GenericClass *>(function_to_bind);
 		// MSVC, SunC++ and DMC accept the following (non-standard) code:
 //		m_pthis = static_cast<GenericClass *>(static_cast<void *>(function_to_bind));
@@ -793,7 +793,7 @@ public:
 		// Ensure that there's a compilation failure if function pointers 
 		// and data pointers have different sizes.
 		// If you get this error, you need to #undef FASTDELEGATE_USESTATICFUNCTIONHACK.
-		typedef int ERROR_CantUseEvilMethod[sizeof(UnvoidStaticFuncPtr)==sizeof(this) ? 1 : -1];
+		typedef int ERROR_CantUseEvilMethod[sizeof(UnvoidStaticFuncPtr)==sizeof(this) ? 1 : -1] __attribute((unused));
 		return horrible_cast<UnvoidStaticFuncPtr>(this);
 	}
 #endif // !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)