Be more forceful in checking for XInput2.1. Fixes build on

NetBSD-6.1.5 with native X.  PR pkg/49986.

print/xdvik/distinfo

@@ -1,7 +1,8 @@
-$NetBSD: distinfo,v 1.8 2015/06/14 12:50:07 markd Exp $
+$NetBSD: distinfo,v 1.9 2015/06/22 21:28:38 markd Exp $
 
 SHA1 (texlive-20150521-source.tar.xz) = a32df8d5d6b61f87f7dab907e864fb51b14f4143
 RMD160 (texlive-20150521-source.tar.xz) = fced0e58a7bd15d19e11d72baed23ac14fd2be13
 Size (texlive-20150521-source.tar.xz) = 45459552 bytes
 SHA1 (patch-aa) = 08bc8e8a7a2cd7a65c0a176f02fdd2930d1d9ae2
 SHA1 (patch-ab) = bbbeb011aa888f2ee7dab84c1602fb3e1127cdb1
+SHA1 (patch-configure) = bd3b6309a60ea8173cb020335f7337abbda07103

print/xdvik/patches/patch-configure

@@ -0,0 +1,14 @@
+$NetBSD: patch-configure,v 1.1 2015/06/22 21:28:38 markd Exp $
+
+--- configure.orig	2015-03-12 14:42:02.000000000 +0000
++++ configure
+@@ -15788,6 +15788,9 @@ LDFLAGS="$X_LIBS $LDFLAGS"
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ /* end confdefs.h.  */
+ #include <X11/extensions/XInput2.h>
++#ifndef XIScrollClass
++ bollocks
++#endif
+ int
+ main ()
+ {