po: do not translate ""

For the umpteenth time, this does NOT work. "" is special in gettext.
Furthermore, use of conditionals is not allowed within gettext macros.

modules/gui/macosx/prefs.m

@@ -487,7 +487,7 @@ static VLCPrefs *_o_sharedMainInstance = nil;
 @implementation VLCTreePluginItem
 - (id)initWithPlugin:(module_t *)plugin
 {
-    NSString * name = _NS( module_get_name( plugin, false )?:"" );
+    NSString * name = _NS( module_get_name( plugin, false ) );
     if(self = [super initWithName:name])
     {
         _configItems = module_config_get( plugin, &_configSize );

modules/gui/macosx/simple_prefs.m

@@ -448,7 +448,7 @@ static inline char * __config_GetLabel( vlc_object_t *p_this, const char *psz_na
 - (void)setupButton: (NSButton *)object forBoolValue: (const char *)name
 {
     [object setState: config_GetInt( p_intf, name )];
-    [object setToolTip: _NS(config_GetLabel( p_intf, name ) ?: "")];
+    [object setToolTip: _NS(config_GetLabel( p_intf, name ))];
 }
 
 - (void)setupField:(NSTextField *)o_object forOption:(const char *)psz_option