Add opaque ID structure.

Move the IP, email and host checking fields from the public
X509_VERIFY_PARAM structure into an opaque X509_VERIFY_PARAM_ID
structure. By doing this the structure can be modified in future
without risk of breaking any applications.
(cherry picked from commit adc6bd73e3bd10ce6e76867482e8d137071298d7)

Conflicts:

	crypto/x509/x509_vpm.c