Finally fix missionpack compiling for STANDALONE=1, yes, this is tested.

code/client/client.h

@@ -456,9 +456,7 @@ int CL_GetPingQueueCount( void );
 
 void CL_ShutdownRef( void );
 void CL_InitRef( void );
-#ifndef STANDALONE
 qboolean CL_CDKeyValidate( const char *key, const char *checksum );
-#endif
 int CL_ServerStatus( char *serverAddress, char *serverStatusString, int maxLen );
 
 qboolean CL_CheckPaused(void);