Issues with current implementation of X509_PURPOSE constants

[bkstein]

I'm in the process of updating my PR #1598 branch and hit a problem with the implementation of X509_PURPOSE_xxx constants (

rust-openssl/openssl/src/x509/verify.rs

Line 197 in 2c0c391

pub struct X509PurposeFlags: c_int {

).
First, these are currently implemented as bitflags!, but the way I see it, these constants are no bitflags. It compiles, but people might try to | the flags.
Second, there is an OpenSSL version restriction (#[cfg(ossl102)]) on the constants, but these constants already existed in 0.9.8 (and probably even earlier, but that's the oldest version I have checked out).
I wouldn't complain, but I have also implemented X509_PURPOSE_xxx in PR #1598 and now I have a conflict: shall I keep the existing version or shall I replace it with mine?

[sfackler]

Yeah, those definitely shouldn't be bitflags. Fortunately, there hasn't been a release with that type added yet, so we can just change it.

[bkstein]

I will make a PR for this. I also think, it is better to move the X509_PURPOSE definitions from x509/verify.rs to x509/mod.rs, as it is also used by store.rs (X509StoreBuilderRef::set_purpose()).

[bkstein]

Should be fixed with #1788.