It was determined through testing that `XXH64_update` is
significantly slower than calling `XXH64` directly as far as small
data velocity is concerned. This function is called on every RP end
which made it visible while profiling but substantial difference
(measured to be ~4x) made it not show up whatsoever.
Signed-off-by: Mark Collins <mark@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18428>