Removed build_distance_tables return value

[radarhere]

build_distance_tables only ever returns 1 -

Pillow/src/libImaging/Quant.c

Lines 792 to 815 in 9b69d94

	static int
	build_distance_tables(
	uint32_t *avgDist, uint32_t **avgDistSortKey, Pixel *p, uint32_t nEntries) {
	uint32_t i, j;
	for (i = 0; i < nEntries; i++) {
	avgDist[i * nEntries + i] = 0;
	avgDistSortKey[i * nEntries + i] = &(avgDist[i * nEntries + i]);
	for (j = 0; j < i; j++) {
	avgDist[j * nEntries + i] = avgDist[i * nEntries + j] =
	_DISTSQR(p + i, p + j);
	avgDistSortKey[j * nEntries + i] = &(avgDist[j * nEntries + i]);
	avgDistSortKey[i * nEntries + j] = &(avgDist[i * nEntries + j]);
	}
	}
	for (i = 0; i < nEntries; i++) {
	qsort(
	avgDistSortKey + i * nEntries,
	nEntries,
	sizeof(uint32_t *),
	_sort_ulong_ptr_keys);
	}
	return 1;
	}

So this PR removes the return value.