CryptoPkg/BaseCryptLib: Use X509_V_FLAG_PARTIAL_CHAIN

CryptoPkg/BaseCryptLib: Use X509_V_FLAG_PARTIAL_CHAIN

Since OpenSSL 1.0.2 we can set this flag on the X509_STORE to instruct
OpenSSL to accept non-self-signed certificates as trusted. So we don't
need two entirely identical copies of a verify_cb() function which makes
it ignore the resulting errors.

We also *didn't* use that verify_cb() function for X509VerifyCert(), but
probably should have done. So that can get X509_V_FLAG_PARTIAL_CHAIN for
consistency, too.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Reviewed-by: Qin Long <qin.long@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18703 6f19259b-4bc3-4df7-8a09-765794883524