War on -Werror, part 12: explicit bool usage.

It may save a few cycles, but it's best to be
explicit on boolean operations, especially with
ASSERT.

src/ScreenServiceAction.cpp

@@ -425,7 +425,7 @@ void ScreenServiceAction::BeginScreen()
 		else if( *s == "SyncEditsMachineToMemoryCard" )		pfn = SyncEditsMachineToMemoryCard;
 		else if( *s == "ResetPreferences" )			pfn = ResetPreferences;
 		
-		ASSERT_M( pfn, *s );
+		ASSERT_M( pfn != NULL, *s );
 		
 		RString sResult = pfn();
 		vsResults.push_back( sResult );