Revert "mesa: Require mipmap completeness for glCopyImageSubData(), sometimes."

This reverts commit c5bf7cb529.

This broke rendering in "Total War: WARHAMMER", which uses a single
level RGBA_UINT32 texture and the default filter modes of GL_LINEAR
and GL_NEAREST_MIPMAP_LINEAR.  However, the texture max level is 0,
so it is actually mipmap complete - it's the integer + linear rule
that causes the error.

I'm working with Khronos to find a real solution.  However it turns
out, this patch is not correct and breaks real programs, so let's
revert it for now.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100690
Bugzilla: https://cvs.khronos.org/bugzilla/show_bug.cgi?id=16224
Cc: "17.1" <mesa-stable@lists.freedesktop.org>

src/mesa/main/copyimage.c

@@ -149,30 +149,9 @@ prepare_target(struct gl_context *ctx, GLuint name, GLenum target,
          return false;
       }
 
-      /* The ARB_copy_image specification says:
-       *
-       *    "INVALID_OPERATION is generated if either object is a texture and
-       *     the texture is not complete (as defined in section 3.9.14)"
-       *
-       * The cited section says:
-       *
-       *    "Using the preceding definitions, a texture is complete unless any
-       *     of the following conditions hold true: [...]
-       *
-       *     * The minification filter requires a mipmap (is neither NEAREST
-       *       nor LINEAR), and the texture is not mipmap complete."
-       *
-       * This imposes the bizarre restriction that glCopyImageSubData requires
-       * mipmap completion at times, which dEQP mandates, and other drivers
-       * appear to implement.  We don't have any texture units here, so we
-       * can't look at any bound separate sampler objects...it appears that
-       * you're supposed to use the sampler object which is built-in to the
-       * texture object.
-       *
-       * See https://cvs.khronos.org/bugzilla/show_bug.cgi?id=16224.
-       */
       _mesa_test_texobj_completeness(ctx, texObj);
-      if (!_mesa_is_texture_complete(texObj, &texObj->Sampler)) {
+      if (!texObj->_BaseComplete ||
+          (level != 0 && !texObj->_MipmapComplete)) {
          _mesa_error(ctx, GL_INVALID_OPERATION,
                      "glCopyImageSubData(%sName incomplete)", dbg_prefix);
          return false;