wined3d: Get rid of the useless "isPBuffer" bitfield in struct wined3d_context.

dlls/wined3d/context.c

@@ -698,7 +698,7 @@ static void context_destroy_gl_resources(struct wined3d_context *context)
         ERR("Failed to disable GL context.\n");
     }
 
-    if (context->isPBuffer)
+    if (context->pbuffer)
     {
         GL_EXTCALL(wglReleasePbufferDCARB(context->pbuffer, context->hdc));
         GL_EXTCALL(wglDestroyPbufferARB(context->pbuffer));
@@ -1250,7 +1250,6 @@ struct wined3d_context *CreateContext(IWineD3DDeviceImpl *This, IWineD3DSurfaceI
     ret->gl_info = &This->adapter->gl_info;
     ret->surface = (IWineD3DSurface *) target;
     ret->current_rt = (IWineD3DSurface *)target;
-    ret->isPBuffer = create_pbuffer;
     ret->tid = GetCurrentThreadId();
     if(This->shader_backend->shader_dirtifyable_constants((IWineD3DDevice *) This)) {
         /* Create the dirty constants array and initialize them to dirty */

dlls/wined3d/wined3d_private.h

@@ -1051,7 +1051,6 @@ struct wined3d_context
     WORD last_was_blit : 1;
     WORD last_was_ckey : 1;
     WORD fog_coord : 1;
-    WORD isPBuffer : 1;
     WORD fog_enabled : 1;
     WORD num_untracked_materials : 2;   /* Max value 2 */
     WORD current : 1;