video_text: Fix a bad vasprintf usage.

src/video_output/video_text.c

@@ -127,7 +127,7 @@ void __vout_OSDMessage( vlc_object_t *p_caller, int i_channel,
                         const char *psz_format, ... )
 {
     vout_thread_t *p_vout;
-    char *psz_string;
+    char *psz_string = NULL;
     va_list args;
 
     if( !config_GetInt( p_caller, "osd" ) ) return;
@@ -136,17 +136,17 @@ void __vout_OSDMessage( vlc_object_t *p_caller, int i_channel,
     if( p_vout )
     {
         va_start( args, psz_format );
-        vasprintf( &psz_string, psz_format, args );
-
+        if( vasprintf( &psz_string, psz_format, args ) != -1 )
+        {
             vout_ShowTextRelative( p_vout, i_channel, psz_string, NULL,
                                    OSD_ALIGN_TOP|OSD_ALIGN_RIGHT,
                                    30 + p_vout->fmt_in.i_width
                                       - p_vout->fmt_in.i_visible_width
                                       - p_vout->fmt_in.i_x_offset,
                                    20 + p_vout->fmt_in.i_y_offset, 1000000 );
-
-        vlc_object_release( p_vout );
             free( psz_string );
+        }
+        vlc_object_release( p_vout );
         va_end( args );
     }
 }