hdr_historgram_log: fix 3 memory leaks on histogram-counts

[DavidKorczynski]

The fuzzer from #120 found some leaks when the hdr_decode_compressed* functions call hdr_init but later fails and cleans up h by way of hdr_free(h). The problem is that the counts field on the histogram is leaked, which is allocated here:

HdrHistogram_c/src/hdr_histogram.c

Line 424 in 8dcce8f

counts = (int64_t*) hdr_calloc((size_t) cfg.counts_len, sizeof(int64_t));

and assigned to the counts field here:

HdrHistogram_c/src/hdr_histogram.c

Line 437 in 8dcce8f

histogram->counts = counts;

Instead of using hdr_free the cleanup function should be `hdr_close:

HdrHistogram_c/src/hdr_histogram.c

Lines 445 to 451 in 8dcce8f

	void hdr_close(struct hdr_histogram* h)
	{
	if (h) {
	hdr_free(h->counts);
	hdr_free(h);
	}
	}