on DU4.0d/alpha, gethostbyname_r is only declared with -D_REENTRANT

[Tom Tromey]

>>>>> "Alexandre" == Alexandre Oliva <oliva@dcc.unicamp.br> writes:

Alexandre> And it is very good that it fails to compile!  After
Alexandre> arranging that _REENTRANT is declared, I found out the
Alexandre> signature is completely different.  Here's a patch that
Alexandre> adds support for DU4's gethostby{name,addr}_r:

Thanks, I'm committing this.  I don't think it is fully the right fix,
but it will do for now.  I think we ought to define _REENTRANT
whenever we are using POSIX threads.  I've submitted a PR to this
effect.

Tom