Fix off by one in calculation of the number of buckets for the pc addresses.

[kib]

Summary

This issue caused the assertion at the line 498 to be triggered:

	bucket = (cc[0] - map->ppm_lowpc) / FUNCTION_ALIGNMENT;
	assert(bucket < pgf->pgf_nbuckets);

when cc value appears at the top of the image.

I triggered it with the pmcstat -R log -g.