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/AttackDisplay.cpp

@@ -46,7 +46,7 @@ void AttackDisplay::Init( const PlayerState* pPlayerState )
 	for( int al=0; al<NUM_ATTACK_LEVELS; al++ )
 	{
 		const Character *ch = GAMESTATE->m_pCurCharacters[pn];
-		ASSERT( ch );
+		ASSERT( ch != NULL );
 		const RString* asAttacks = ch->m_sAttacks[al];
 		for( int att = 0; att < NUM_ATTACKS_PER_LEVEL; ++att )
 			attacks.insert( asAttacks[att] );