CryptoPkg/BaseCryptLib: Use accessor functions for X509_ATTRIBUTE

CryptoPkg/BaseCryptLib: Use accessor functions for X509_ATTRIBUTE

In OpenSSL 1.1, the X509_ATTRIBUTE becomes an opaque structure and we will
no longer get away with accessing its members directly. Use the accessor
functions X509_ATTRIBUTE_get0_object0() and X509_ATTRIBUTE_get0_type()
instead.

Also be slightly more defensive about unlikely failure modes.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Qin Long <qin.long@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18700 6f19259b-4bc3-4df7-8a09-765794883524