misc/52422: fuse.h cannot be included by itself

[coypu%sdf.org@localhost]

>Number:         52422
>Category:       misc
>Synopsis:       fuse.h cannot be included by itself
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    misc-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 20 14:30:00 +0000 2017
>Originator:     coypu
>Release:        NetBSD 8.99.1
>Organization:
>Environment:
NetBSD loggy 8.99.1 NetBSD 8.99.1 (GENERIC) #82: Thu Jun 22 15:45:33 IDT 2017  fly@loggy:/home/fly/obj/sys/arch/amd64/compile/GENERIC amd64

>Description:
$ cat mygreatfilesystem.c
#include <fuse.h>
int main() { return 0; }

$ gcc mygreatfilesystem.c 
In file included from /usr/include/puffs.h:44:0,
                 from /usr/include/fuse.h:41,
                 from mygreatfilesystem.c:1:
/usr/include/fs/puffs/puffs_msgif.h:595:2: error: unknown type name ?register_t?
  register_t  pvnr_retval;  /* IN */
  ^
In file included from /usr/include/fuse.h:41:0,
                 from mygreatfilesystem.c:1:
/usr/include/puffs.h:225:27: error: unknown type name ?register_t?
      puffs_cookie_t, int, register_t *);
                           ^
/usr/include/puffs.h:436:1: error: unknown type name ?register_t?
 PUFFSOP_PROTOS(puffs_null) /* XXX */
 ^
/usr/include/puffs.h:505:20: error: unknown type name ?vsize_t?
        enum vtype, vsize_t, dev_t); 
                    ^


as a workaround, define _KMEMUSER. not ideal.
>How-To-Repeat:

>Fix: