* cygheap.h (cygheap_fdnew): Avoid setting errno directly since it will have

* cygheap.h (cygheap_fdnew): Avoid setting errno directly since it will have
been set by a previous function.
* dtable.h (dtable::extend): Accept second size_t argument.
* dtable.cc (dtable::extend): Accept second "min" argument which allows
checking for OPEN_MAX_MAX boundary conditions.
(dtable_init): Accommodate second argument to dtable::extend.
(dtable::find_unused_handle): Ditto.
* syscalls.cc (setdtablesize): Ditto.
(dup): Return any error passed by cygheap_fdnew() directly.
(getdtablesize): Just return dtable size directly.