VAAPI: do not crash when vlc_va_Initialize fails.

Upon failure of vlc_va_Initialize() the error path jumped to the label 'error',
which would call sys->conn->unlock(). However the error path was taken before
sys->conn->lock() was called and even worse sys->conn = NULL in this case. This
would result into crash obviously. Therefor move the 'error' label one line down,
so it only calls the cleanup routions and add a lable 'unlock' for the error paths
that need to unlock first before cleaning up.

modules/codec/avcodec/vaapi.c

@@ -149,7 +149,7 @@ static int Open( vlc_va_vaapi_t *p_va, int i_codec_id, int i_count )
     int i_profiles_nb = vaMaxNumProfiles( p_va->conn->p_display );
     VAProfile *p_profiles_list = calloc( i_profiles_nb, sizeof( VAProfile ) );
     if ( !p_profiles_list )
-        goto error;
+        goto unlock;
     VAStatus status = vaQueryConfigProfiles( p_va->conn->p_display, p_profiles_list, &i_profiles_nb );
     if ( status == VA_STATUS_SUCCESS )
     {
@@ -164,7 +164,7 @@ static int Open( vlc_va_vaapi_t *p_va, int i_codec_id, int i_count )
     }
     free( p_profiles_list );
     if ( !b_supported_profile )
-        goto error;
+        goto unlock;
 
     /* Create a VA configuration */
     VAConfigAttrib attrib;
@@ -172,16 +172,16 @@ static int Open( vlc_va_vaapi_t *p_va, int i_codec_id, int i_count )
     attrib.type = VAConfigAttribRTFormat;
     if( vaGetConfigAttributes( p_va->conn->p_display,
                                i_profile, VAEntrypointVLD, &attrib, 1 ) )
-        goto error;
+        goto unlock;
 
     /* Not sure what to do if not, I don't have a way to test */
     if( (attrib.value & VA_RT_FORMAT_YUV420) == 0 )
-        goto error;
+        goto unlock;
     if( vaCreateConfig( p_va->conn->p_display,
                         i_profile, VAEntrypointVLD, &attrib, 1, &p_va->i_config_id ) )
     {
         p_va->i_config_id = VA_INVALID_ID;
-        goto error;
+        goto unlock;
     }
 
     p_va->i_surface_count = i_surface_count;
@@ -193,8 +193,9 @@ static int Open( vlc_va_vaapi_t *p_va, int i_codec_id, int i_count )
     p_va->conn->unlock();
     return VLC_SUCCESS;
 
-error:
+unlock:
     p_va->conn->unlock();
+error:
     Close(p_va);
     return VLC_EGENERIC;
 }