When calling X509_set_version to set v1 certificate, that should mean
that the version number field is omitted.

(Imported from upstream's 8c0d19d857)

Change-Id: If433fda7b6ccbd899f3379a38581c351cf4a82da

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)