xf86drm: Fix type-punned pointer build warning

      CC       libdrm_la-xf86drmMode.lo
    ../xf86drmMode.c: In function 'drmHandleEvent':
    ../xf86drmMode.c:854:15: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
       e = (struct drm_event *)(&buffer[i]);
                   ^

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99350
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/xf86drmMode.c b/xf86drmMode.c
index fb22f68..0266bc1 100644
--- a/xf86drmMode.c
+++ b/xf86drmMode.c
@@ -901,7 +901,7 @@
 
 	i = 0;
 	while (i < len) {
-		e = (struct drm_event *) &buffer[i];
+		e = (struct drm_event *)(buffer + i);
 		switch (e->type) {
 		case DRM_EVENT_VBLANK:
 			if (evctx->version < 1 ||