2.5.6pre1 bombs on Sunos4 in popthelp.c on use of sprintf

[Dave Dykstra]

2.5.6pre1 bombs on Sunos4 gcc with these errors
    popt/popthelp.c: In function `singleOptionDefaultValue':
    popt/popthelp.c:137: invalid operands to binary +
    popt/popthelp.c:141: invalid operands to binary +
    popt/popthelp.c:145: invalid operands to binary +
    popt/popthelp.c:149: invalid operands to binary +
because it's depending on sprintf to return the number of bytes written
and that doesn't happen on Sunos4.

Wayne or anybody, do you have a suggested solution?  The popt maintainers
should also be told about that.  This foible of Sunos4 is mentioned in
the autoconf documentation of things to watch out for but I don't think
they suggest a solution.

We need to get one of these Sunos4 machines into the build farm.  I know
where to get one, but I had been hesitant to add machines to the build
farm because of security concerns.  I think the new rsync module over
ssh feature will eliminate those concerns.

- Dave