SecurityPkg/DxeImageVerificationLib: reject CertStack.CertNumber==0 per DBX (CVE-2019-14575)
In case the signers' certificate stack, retrieved from the PE/COFF image's
Authenticode blob, has zero elements (=there are zero signer certificates),
then we should consider the image forbidden by DBX, not accepted by DBX.
Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Chao Zhang <chao.b.zhang@intel.com> Signed-off-by: Jian J Wang <jian.j.wang@intel.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>