[newlib-cygwin] Add 32-bit compat for ioctls that take struct ifgroupreq.

[Sebastian Huber <sh@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=341e131f7fec9f5c1f17745bfe3c324029034348

commit 341e131f7fec9f5c1f17745bfe3c324029034348
Author: brooks <brooks@FreeBSD.org>
Date:   Thu Apr 5 22:14:55 2018 +0000

    Add 32-bit compat for ioctls that take struct ifgroupreq.
    
    Use an accessor to access ifgr_group and ifgr_groups.
    
    Use an macro CASE_IOC_IFGROUPREQ(cmd) in place of case statements such
    as "case SIOCAIFGROUP:". This avoids poluting the switch statements
    with large numbers of #ifdefs.
    
    Reviewed by:	kib
    Obtained from:	CheriBSD
    MFC after:	1 week
    Sponsored by:	DARPA, AFRL
    Differential Revision:	https://reviews.freebsd.org/D14960

Diff:
---
 newlib/libc/sys/rtems/include/net/if.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/newlib/libc/sys/rtems/include/net/if.h b/newlib/libc/sys/rtems/include/net/if.h
index d88003b..83a4328 100644
--- a/newlib/libc/sys/rtems/include/net/if.h
+++ b/newlib/libc/sys/rtems/include/net/if.h
@@ -517,8 +517,10 @@ struct ifgroupreq {
 		char	ifgru_group[IFNAMSIZ];
 		struct	ifg_req *ifgru_groups;
 	} ifgr_ifgru;
+#ifndef _KERNEL
 #define ifgr_group	ifgr_ifgru.ifgru_group
 #define ifgr_groups	ifgr_ifgru.ifgru_groups
+#endif
 };
 
 /*