mesa/main: fix error checking logic on CopyImageSubData

For the case (both src or dst) where we had a texobject, but the
texobject target was not the same that the method target, this spec
paragraph was appplied:

 /* Section 18.3.2 (Copying Between Images) of the OpenGL 4.5 Core
  * Profile spec says:
  *
  *     "An INVALID_VALUE error is generated if either name does not
  *     correspond to a valid renderbuffer or texture object according
  *     to the corresponding target parameter."
  */

But for that case, the correct spec paragraph should be:
 /* Section 18.3.2 (Copying Between Images) of the OpenGL 4.5 Core
  * Profile spec says:
  *
  *     "An INVALID_ENUM error is generated if either target is
  *      not RENDERBUFFER or a valid non-proxy texture target;
  *      is TEXTURE_BUFFER or one of the cubemap face selectors
  *      described in table 8.18; or if the target does not
  *      match the type of the object."
  */

specifically the last sentence: "or if the target does not match the
type of the object".

This patch fixes the error returned (s/INVALID/ENUM) for that case,
and moves up the INVALID_VALUE spec paragraph, as that case (invalid
texture object) was handled before.

Fixes:
GL44-CTS.copy_image.target_miss_match

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/mesa/main/copyimage.c

@@ -138,6 +138,12 @@ prepare_target(struct gl_context *ctx, GLuint name, GLenum target,
       struct gl_texture_object *texObj = _mesa_lookup_texture(ctx, name);
 
       if (!texObj) {
+         /*
+          * From GL_ARB_copy_image specification:
+          * "INVALID_VALUE is generated if either <srcName> or <dstName> does
+          * not correspond to a valid renderbuffer or texture object according
+          * to the corresponding target parameter."
+          */
          _mesa_error(ctx, GL_INVALID_VALUE,
                      "glCopyImageSubData(%sName = %u)", dbg_prefix, name);
          return false;
@@ -154,12 +160,11 @@ prepare_target(struct gl_context *ctx, GLuint name, GLenum target,
       /* Note that target will not be a cube face name */
       if (texObj->Target != target) {
          /*
-          * From GL_ARB_copy_image specification:
-          * "INVALID_VALUE is generated if either <srcName> or <dstName> does
-          * not correspond to a valid renderbuffer or texture object according
-          * to the corresponding target parameter."
+          * From GL_ARB_copy_image_specification:
+          * "INVALID_ENUM is generated if the target does not match the type
+          * of the object."
           */
-         _mesa_error(ctx, GL_INVALID_VALUE,
+         _mesa_error(ctx, GL_INVALID_ENUM,
                      "glCopyImageSubData(%sTarget = %s)", dbg_prefix,
                      _mesa_enum_to_string(target));
          return false;