OpenBSD fix for fopencookie

[Matt Jibson]

I am attempting to lilypond 2.5 to OpenBSD. One of the problems I'm 
running into is that the BSDs don't have the fopencookie function and 
libio.h. The BSD equivalent is funopencookie. The offending files are 
flower/memory-stream.cc and .hh. I looked in the PHP codebase to see how 
they handle this problem. In main/streams.c, PHP has:

/* Under BSD, emulate fopencookie using funopen */
#if HAVE_FUNOPEN
typedef struct {
   int (*reader)(void *, char *, int);
   int (*writer)(void *, const char *, int);
   fpos_t (*seeker)(void *, fpos_t, int);
   int (*closer)(void *);
} COOKIE_IO_FUNCTIONS_T;

FILE *fopencookie(void *cookie, const char *mode, COOKIE_IO_FUNCTIONS_T 
*funcs)
{
   return funopen(cookie, funcs->reader, funcs->writer, funcs->seeker, 
funcs->closer);
}
# define HAVE_FOPENCOOKIE 1
# define PHP_STREAM_COOKIE_FUNCTIONS    &stream_cookie_functions
#elif HAVE_FOPENCOOKIE
# define PHP_STREAM_COOKIE_FUNCTIONS    stream_cookie_functions
#endif

[...]

#if HAVE_FOPENCOOKIE
static COOKIE_IO_FUNCTIONS_T stream_cookie_functions =
{
   stream_cookie_reader, stream_cookie_writer,
   stream_cookie_seeker, stream_cookie_closer
};
#else
/* TODO: use socketpair() to emulate fopencookie, as suggested by 
Hartmut ? */
#endif

------

I have tried figure out how to make these modifications work with 
lilypond, but I'm not versed enough in this type of C++ to get it to 
work. Could someone help me out with fixes to flower/memory-stream.cc 
and .hh so that I can complete the lilypond port? Thanks.

-Matt Jibson