Fix build on *BSD
This adds a minimal #ifdef clause to drm.h that we'll push upstream.
Once that goes in we can share drm.h between linux, libdrm, and
the bsd's.
diff --git a/xf86drm.h b/xf86drm.h
index 2cb9c9e..cf7d132 100644
--- a/xf86drm.h
+++ b/xf86drm.h
@@ -39,6 +39,28 @@
#include <stdint.h>
#include <drm.h>
+#if defined(__linux__)
+
+#define DRM_IOCTL_NR(n) _IOC_NR(n)
+#define DRM_IOC_VOID _IOC_NONE
+#define DRM_IOC_READ _IOC_READ
+#define DRM_IOC_WRITE _IOC_WRITE
+#define DRM_IOC_READWRITE _IOC_READ|_IOC_WRITE
+#define DRM_IOC(dir, group, nr, size) _IOC(dir, group, nr, size)
+#define DRM_MAJOR 226
+
+#else /* One of the *BSDs */
+
+#include <sys/ioccom.h>
+#define DRM_IOCTL_NR(n) ((n) & 0xff)
+#define DRM_IOC_VOID IOC_VOID
+#define DRM_IOC_READ IOC_OUT
+#define DRM_IOC_WRITE IOC_IN
+#define DRM_IOC_READWRITE IOC_INOUT
+#define DRM_IOC(dir, group, nr, size) _IOC(dir, group, nr, size)
+
+#endif
+
/* Defaults, if nothing set in xf86config */
#define DRM_DEV_UID 0
#define DRM_DEV_GID 0