l2tpv3 (configure): it is linux-specific

Some non-linux systems, for example a system with
FreeBSD kernel and glibc, may declare struct mmsghdr
(in glibc) but may not have linux-specific header
file linux/ip.h.  The actual implementation in qemu
includes this linux-specific header file unconditionally,
so compilation fails if it is not present.  Include
this header in the configure test too.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/configure b/configure
index f7685b565cff8256b3bb1bcfb1035c52dafe3ff2..f49e61888e3c9e90f703fb7844500fe67477d259 100755 (executable)
--- a/configure
+++ b/configure
@@ -1723,6 +1723,7 @@ fi
 
 cat > $TMPC <<EOF
 #include <sys/socket.h>
+#include <linux/ip.h>
 int main(void) { return sizeof(struct mmsghdr); }
 EOF
 if compile_prog "" "" ; then