[gupnp] gupnp-linux-context-manager.c: fix {linux, net}/if.h redefinition

[Jens Georg <jensgeorg src gnome org>]

commit 8fdfc7ef6b7e4401e9b5c72c1a215bb8f492ad4d
Author: Fabrice Fontaine <fontaine fabrice gmail com>
Date:   Thu Aug 1 22:52:11 2019 +0200

    gupnp-linux-context-manager.c: fix {linux,net}/if.h redefinition
    
    Do not include net/if.h if linux/wireless.h is available otherwise build
    will fail due to redefinitions like struct ifmap:
    
    In file included from 
/home/fabrice/buildroot/output/host/mips64el-buildroot-linux-gnu/sysroot/usr/include/linux/wireless.h:74:0,
                     from ../libgupnp/gupnp-linux-context-manager.c:52:
    /home/fabrice/buildroot/output/host/mips64el-buildroot-linux-gnu/sysroot/usr/include/linux/if.h:169:8: 
error: redefinition of 'struct ifmap'
     struct ifmap {
            ^
    In file included from ../libgupnp/gupnp-linux-context-manager.c:50:0:
    /home/fabrice/buildroot/output/host/mips64el-buildroot-linux-gnu/sysroot/usr/include/net/if.h:111:8: 
note: originally defined here
     struct ifmap
    
    Signed-off-by: Fabrice Fontaine <fontaine fabrice gmail com>

 libgupnp/gupnp-linux-context-manager.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/libgupnp/gupnp-linux-context-manager.c b/libgupnp/gupnp-linux-context-manager.c
index 5b03118..e96ec66 100644
--- a/libgupnp/gupnp-linux-context-manager.c
+++ b/libgupnp/gupnp-linux-context-manager.c
@@ -47,9 +47,10 @@
 #include <sys/socket.h>
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
-#include <net/if.h>
 #ifdef HAVE_LINUX_WIRELESS_H
 #include <linux/wireless.h>
+#else
+#include <net/if.h>
 #endif
 #include <sys/ioctl.h>
 #include <errno.h>