This moves the POPCOUNTL macro from cogl-winsys-glx to cogl-util and
renames it to _cogl_util_popcountl so that it can be used in more
places. The fallback function for when the GCC builtin is not
available has been replaced with an 8-bit lookup table because the
HAKMEM implementation doesn't look like it would work when longs are
64-bit so it's not suitable for a general purpose function on 64-bit
architectures. Some of the pages regarding population counts seem to
suggest that using a lookup table is the fastest method anyway.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
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