Qt4: use putenv() before any thread is created

bin/vlc.c

@@ -89,6 +89,10 @@ int main( int i_argc, const char *ppsz_argv[] )
 #   endif
 #endif
 
+    /* Make Xlib hide visuals with an alphachannel. Ensure that Qt4 will not
+     * use the alpha channel for the embedded video window. */
+    putenv( (char *)"XLIB_SKIP_ARGB_VISUALS=1" );
+
     /* Synchronously intercepted POSIX signals.
      *
      * In a threaded program such as VLC, the only sane way to handle signals

modules/gui/qt4/qt4.cpp

@@ -295,7 +295,6 @@ static int Open( vlc_object_t *p_this, bool isDialogProvider )
         return VLC_EGENERIC;
     }
     XCloseDisplay( p_display );
-    putenv( (char *)"XLIB_SKIP_ARGB_VISUALS=1" );
 #else
     char *display = NULL;
 #endif