Pick up dri2proto from the standard proto header include path.
diff --git a/configure.ac b/configure.ac
index 8598a0d..48921e0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -388,7 +388,7 @@
 
     # Check for libdrm
     PKG_CHECK_MODULES(LIBDRM, libdrm)
-    PKG_CHECK_MODULES(DRI2PROTO, dri2proto)
+    PKG_CHECK_MODULES(DRI2PROTO, dri2proto >= 1.1)
 
     # find the DRI deps for libGL
     if test "$x11_pkgconfig" = yes; then