[newlib-cygwin] Use an accessor function to access ifr_data.

[Sebastian Huber <sh@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=79291d61231f00ab41298aa0b20e1a42cb8c5c05

commit 79291d61231f00ab41298aa0b20e1a42cb8c5c05
Author: brooks <brooks@FreeBSD.org>
Date:   Fri Mar 30 18:50:13 2018 +0000

    Use an accessor function to access ifr_data.
    
    This fixes 32-bit compat (no ioctl command defintions are required
    as struct ifreq is the same size).  This is believed to be sufficent to
    fully support ifconfig on 32-bit systems.
    
    Reviewed by:	kib
    Obtained from:	CheriBSD
    MFC after:	1 week
    Relnotes:	yes
    Sponsored by:	DARPA, AFRL
    Differential Revision:	https://reviews.freebsd.org/D14900

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 e9e6391..d88003b 100644
--- a/newlib/libc/sys/rtems/include/net/if.h
+++ b/newlib/libc/sys/rtems/include/net/if.h
@@ -412,7 +412,9 @@ struct	ifreq {
 #define	ifr_mtu		ifr_ifru.ifru_mtu	/* mtu */
 #define ifr_phys	ifr_ifru.ifru_phys	/* physical wire */
 #define ifr_media	ifr_ifru.ifru_media	/* physical media */
+#ifndef _KERNEL
 #define	ifr_data	ifr_ifru.ifru_data	/* for use by interface */
+#endif
 #define	ifr_reqcap	ifr_ifru.ifru_cap[0]	/* requested capabilities */
 #define	ifr_curcap	ifr_ifru.ifru_cap[1]	/* current capabilities */
 #define	ifr_index	ifr_ifru.ifru_index	/* interface index */