gnulib's errno module was imported

[Yao Qi <yao@codesourcery.com>]

Hi,
When I audit gnulib modules imported to gdb, I find that errno is in,
which was imported as the dependency of "dirfd" module in commit
18848e288ca9d1ca242cce667419bbb6728442fc  The motivation of importing
"dirfd" module is to make gdb compatible with LSB 3.0 (see
https://sourceware.org/ml/gdb/2014-02/msg00034.html).

However, we've already had a conclusion that we don't import gnulib's
errno module because it has some compatibility issues with libiconv
(discussed in https://sourceware.org/ml/gdb-patches/2012-12/msg00554.html).
AFAICS, the argument that not having errno module at that moment is
still valid today.

I am inclined to back "dirfd" (and "errno") module out.  As a result,
gdb will not be compatible with LSB 3.0, but it is just a minor issue to
me.  What do you think?

-- 
Yao (齐尧)