mapper functions for 3.1

[David Bateman]

David Bateman wrote:
> I believe that lgamma and gamma are the only mapper functions that can
> in fact set error_state and that these two functions are only valid for
> real arguments, and so one solution and the one I'm working on is to
> just not treat gamma and lgamma as mappers but like any other builtin
> function

OK, this isn't a solution as the asinh, etc functions and others also
use the F77_XFCN macro. The only other solution I see at this point is
to move the declaration of error_state.cc from error.cc and into
liboctave.. Do you see any other solutions?

D.