[DRE-maint] Bug#770820: ruby-inotify: FTBFS on arm64

[Edmund Grimley Evans]

Source: ruby-inotify
Version: 0.0.2-7

It failed to build on arm64:

http://buildd.debian.org/status/package.php?p=ruby-inotify&suite=sid

The error was:

ext/inotify.c: In function 'inotify_init':
ext/inotify.c:20:18: error: '__NR_inotify_init' undeclared (first use
in this function)
  return syscall (__NR_inotify_init);
                  ^

There is a similar bug for "inotail":

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=769926

New architectures do not have the system call "inotify_init"; instead
they have "inotify_init1", which takes an extra argument, which you
can set to zero to get the behaviour of "inotify_init".

It's not clear to me why ruby-inotify is using "syscall
(__NR_inotify_init)" instead of just calling the C library's
inotify_init. However, if that's the way you want to do it, you could
replace

    return syscall (__NR_inotify_init);

with:

#ifdef __NR_inotify_init
    return syscall (__NR_inotify_init);
#else
    return syscall (__NR_inotify_init1, 0);
#endif