engine: common: simplify string operations

engine/common/con_utils.c

@@ -1324,8 +1324,9 @@ static void Cmd_WriteHelp(const char *name, const char *unused, const char *desc
 {
 	int	length;
 
-	if( !desc || !Q_strcmp( desc, "" ))
+	if( !COM_CheckString( desc ))
 		return; // ignore fantom cmds
+
 	if( name[0] == '+' || name[0] == '-' )
 		return; // key bindings
 

engine/common/cvar.c

@@ -409,7 +409,7 @@ convar_t *Cvar_Get( const char *name, const char *value, int flags, const char *
 			// which executed from the config file. So we don't need to
 			// change value here: we *already* have actual value from config.
 			// in other cases we need to rewrite them
-			if( Q_strcmp( var->desc, "" ))
+			if( COM_CheckStringEmpty( var->desc ))
 			{
 				// directly set value
 				freestring( var->string );