drm: Introduce a drmSetClientCap() wrapper

That wraps around the new DRM_SET_CLIENT_CAP ioctl.

v2: SET_CAP -> SET_CLIENT_CAP renaming

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
diff --git a/xf86drm.h b/xf86drm.h
index 5ecb284..1e763a3 100644
--- a/xf86drm.h
+++ b/xf86drm.h
@@ -609,6 +609,8 @@
 					   unsigned int num, void *data);
 extern int           drmCtlInstHandler(int fd, int irq);
 extern int           drmCtlUninstHandler(int fd);
+extern int           drmSetClientCap(int fd, uint64_t capability,
+				     uint64_t value);
 
 /* General user-level programmer's API: authenticated client and/or X */
 extern int           drmMap(int fd,