* cygtls.h (unionent): Move from net.cc.

* cygtls.h (unionent): Move from net.cc.
(unionent::struct_type): Move enum here.
(_local_storage::hostent_buf): Define as unionent.
(_local_storage::protoent_buf): Ditto.
(_local_storage::servent_buf): Ditto.
* net.cc (unionent): Move to cygtls.h.
(struct_type): Ditto.
(dup_ent): Define one function per {host,proto,serv}ent type.
(cygwin_getprotobyname): Simplify dup_ent call.  Removed now-unneeded return
type coercion.
(cygwin_getprotobynumber): Ditto.
(cygwin_getservbyname): Ditto.
(cygwin_getservbyport): Ditto.
(cygwin_gethostbyname): Ditto.
(cygwin_gethostbyaddr): Ditto.  tlsoffsets.h: Regenerate.