calc 2.12.6.10 release

The following are the changes in this release:

Added a patch to replaces the manual search for include files
in $(INCDIR) in the have_*.h targets with compiler invocations.
Thanks goes to Helmut Grohne <helmut at subdivi dot de> who
implemented the patch and posted it to the Debian bug tracker
and Martin Buck (m at rtin-buck dor de) for forwarding it to us.

The check_include make rule was fixed to not assume /usr/include.

The qprintnum() function now takes outdigits as a 3rd argument.
Most of the time, this 3rd argument is just conf->outdigits.
But when it comes to the experimental '%g', this value can
change.  This avoids having to modify conf->outdigits.