Fix Makefile ref libseccomp branch as a commit

Commit a824186ac9 mistakenly updated LIBSECCOMP_COMMIT with a branch
name instead of a commit reference.  This breaks on Ubuntu's git with
the `--detach` option, causing it to throw this error:

```
fatal: '--detach' cannot be used with '-b/-B/--orphan'
```

Fix this by using the tag `v2.3.3` which at the time of this commit, is
the current HEAD of the release-2.3 branch.

Thanks to Ed Santiago <santiago@redhat.com> for helping figure
out the error and the fix.

Signed-off-by: Chris Evich <cevich@redhat.com>

0 files changed, 0 insertions, 0 deletions