gzip: simplify by closing ourselves

gzip: simplify by closing ourselves

This simplifies the previous fix, by avoiding the use of the
closein module.  That module was problematic, as gzip normally
does not use stdio for output and never uses it for input.
Also, it is a heavyweight module, as it drags many files into lib
(c-ctype.c, c-ctype.h, closein.c, closein.h, closeout.c, closeout.h,
close-stream.c, close-stream.h, config.charset, c-strcasecmp.c,
c-strcaseeq.h, c-strcase.h, c-strncasecmp.c, fpending.c, fpending.h,
freadahead.c, freadahead.h, localcharset.c, localcharset.h, mbrtowc.c,
mbsinit.c, quotearg.c, quotearg.h, quote.h, ref-add.sin, ref-del.sin,
streq.h, wctype-h.c, wctype.in.h) and into m4 (closein.m4, closeout.m4,
close-stream.m4, codeset.m4, configmake.m4, fpending.m4, freadahead.m4,
glibc21.m4, localcharset.m4, locale-fr.m4, locale-ja.m4, locale-zh.m4,
mbrtowc.m4, mbsinit.m4, mbstate_t.m4, quotearg.m4, wctype_h.m4),
and these files are thus no longer needed.
* bootstrap.conf (gnulib_modules): Remove closein.
* gzip.c: Don't include closein.h.
(stdin_was_read): New static var.
(main): Don't use close_stdin.
Invoke finish_out to exit after outputting via stdio's stdout.
Close stdin after reading it.
Restore previous way of closing stdout.
(treat_stdin): Record that stdin was read.
(finish_out): New function.