It should be HAVE_HUMANIZE_NUMBER instead of HAVE_HUMANIZE_HUMBER, from
the name of humanize_number(3).
It's mispelt only in this file, the configure script gets it correctly.
Closes: #334 [via git-merge-pr]
Along with this change, compat code has been added (from NetBSD)
for systems that don't have it. The compat code has been reorganized
to be in a common place and its prototypes in compat.h.
The configure scripts checks if strcasestr() is available, and
uses compat code if not found.
This fixes issue #2 on github.com/vanilla/xbps.
