X.509: support OSCCA certificate parse

The digital certificate format based on SM2 crypto algorithm as
specified in GM/T 0015-2012. It was published by State Encryption
Management Bureau, China.

This patch adds the OID object identifier defined by OSCCA. The
x509 certificate supports SM2-with-SM3 type certificate parsing.
It uses the standard elliptic curve public key, and the sm2
algorithm signs the hash generated by sm3.

Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Tested-by: Xufeng Zhang <yunbo.xufeng@linux.alibaba.com>
Reviewed-by: Vitaly Chikunov <vt@altlinux.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>