Add fstatfs(64) syscalls to seccomp policies

Due to a local security hardening patch in glibc, we're now
calling fstatfs and fstatfs64 during dlopen. This is crashing
dash and kmod at present, which we _suspect_ some of those
crashes may be due to uncaught errors in touch_updater policies,

Crashes were identified via crash.corp
dash: http://shortn/_eLdGeNd8sp
kmod: http://shortn/_IheitZgfkV

BUG=chromium:1182687
TEST=Check CQ for dash seccomp failures during HW tests

Change-Id: Ie2ac28ca6ba84b94139ec65ae52dd8e3e73a9b7f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/touch_updater/+/3116692
Tested-by: Jordan R Abrahams <ajordanr@google.com>
Commit-Queue: Jordan R Abrahams <ajordanr@google.com>
Reviewed-by: Andrew de los Reyes <adlr@chromium.org>
Reviewed-by: Harry Cutts <hcutts@chromium.org>