Change the logic adjusting the Histogram bits.

Updated the logic to limit the Histogram size to a constant, instead of
computing the same based on the Histogram size (that's variable size based on
the cache bits) for the maximum possible cache bits. The actual cache bits may
be lower than the maximum.
Note: The constant 2600 is 16MB/Sizeof(HistogramSize(MAX_COLOR_CACHE_BITS)).

The compression density remains the same with this change, with little faster
compression speed.

Change-Id: I3149894962852e9dad2501b9aa16bb847a20fd86
1 file changed