O_BINARY no longer defined

[Akim Demaille]

Hi Paul,

Bison no longer compiles cleanly on Travis' Ubuntu Xenial.  Something must have 
changed recently (on Travis): builds that used to pass now fail with 
(https://travis-ci.org/akimd/bison/jobs/569747063):

> In file included from lib/pipe2.c:25:0:
> lib/binary-io.h: In function '__gl_setmode':
> lib/binary-io.h:52:10: error: 'O_BINARY' undeclared (first use in this 
> function)
>    return O_BINARY;
>           ^
> lib/binary-io.h:52:10: note: each undeclared identifier is reported only once 
> for each function it appears in
> lib/pipe2.c: In function 'pipe2':
> lib/pipe2.c:70:43: error: 'O_BINARY' undeclared (first use in this function)
>    if ((flags & ~(O_CLOEXEC | O_NONBLOCK | O_BINARY | O_TEXT)) != 0)
>                                            ^
> lib/pipe2.c:70:54: error: 'O_TEXT' undeclared (first use in this function)
>    if ((flags & ~(O_CLOEXEC | O_NONBLOCK | O_BINARY | O_TEXT)) != 0)
>                                                       ^
> Makefile:4604: recipe for target 'lib/lib_libbison_a-pipe2.o' failed

I have had a quick look at the fcntl-h module, but I don't see anything that 
actually checks whether O_BINARY and O_TEXT are defined (at configure time).

config.log contains:

> configure:13097: checking for working fcntl.h
> configure:13205: gcc -o conftest -g -O2   conftest.c  >&5
> configure:13205: $? = 0
> configure:13205: ./conftest
> configure:13205: $? = 0
> configure:13221: result: yes

so gnulib's fcntl.h is not installed, we use the system's one.  I don't know 
how the module fcntl-h is expected to handle this.

It looks like a job for binary-io.h, but it seems to rely on fcntl.h:

> /* For systems that distinguish between text and binary I/O.
>    O_BINARY is guaranteed by the gnulib <fcntl.h>. */
> #include <fcntl.h>
> 
> [...]
> #if O_BINARY
> # [...]
> #else
>   /* On reasonable systems, binary I/O is the only choice.  */
>   /* Use a function rather than a macro, to avoid gcc warnings
>      "warning: statement with no effect".  */
> BINARY_IO_INLINE int
> __gl_setmode (int fd _GL_UNUSED, int mode _GL_UNUSED)
> {
>   return O_BINARY;
> }
> #endif


Cheers!