mesa: Avoid flagging _NEW_VIEWPORT on redundant viewport updates.
mesa: Avoid flagging _NEW_VIEWPORT on redundant viewport updates.

Cuts the number of i965 color calculator viewport uploads by 100x
(11017983 -> 113385) in 'x11perf -gc' with Glamor in Xephyr.

Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Brian Paul <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@vmware.com>
Reviewed-by: Ian Romanick <2b237cafb16dc45038e85df6c85e74e6d899eba9@intel.com>

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