Merge some file writing extension checks from OpenJK.

Thanks Ensiform.
https://github.com/JACoders/OpenJK/commit/05928a57f9e4aae15a3bd0
https://github.com/JACoders/OpenJK/commit/ef124fd0fc48af164581176
void Com_InitZoneMemory( void ) {
	cvar_t	*cv;


	cv = Cvar_Get( "com_zoneMegs", DEF_COMZONEMEGS_S, CVAR_LATCH | CVAR_ARCHIVE );

	if ( cv->integer < DEF_COMZONEMEGS ) {
		s_zoneTotal = 1024 * 1024 * DEF_COMZONEMEGS;
	} else {
		s_zoneTotal = cv->integer * 1024 * 1024;
	}

	mainzone = calloc( s_zoneTotal, 1 );
	if ( !mainzone ) {
		Com_Error( ERR_FATAL, "Zone data failed to allocate %i megs", s_zoneTotal / (1024*1024) );
	}
	Z_ClearZone( mainzone, s_zoneTotal );

}

void Com_InitZoneMemory( void ) {
	cvar_t	*cv;


	cv = Cvar_Get( "com_zoneMegs", DEF_COMZONEMEGS_S, CVAR_LATCH | CVAR_ARCHIVE );

	if ( cv->integer < DEF_COMZONEMEGS ) {
		s_zoneTotal = 1024 * 1024 * DEF_COMZONEMEGS;
	} else {
		s_zoneTotal = cv->integer * 1024 * 1024;
	}

	mainzone = calloc( s_zoneTotal, 1 );
	if ( !mainzone ) {
		Com_Error( ERR_FATAL, "Zone data failed to allocate %i megs", s_zoneTotal / (1024*1024) );
	}
	Z_ClearZone( mainzone, s_zoneTotal );

}
