macOS cannot create PFX with a mix of HasPrivateKey and !HasPrivateKey certs

[bartonjs]

#24554, but for macOS. (Different fix, and the macOS existing failure is holding up a Linux fix)

var collection = new X509Certificate2Collection();
collection.Add(certificateWithPrivateKey);
collection.Add(anotherCertWithoutPrivateKey);

var output = collection.Export(X509ContentType.Pkcs12);

See also dotnet/corefx#26152.

[Wintereise]

Hi team,

Just wondering if the fix for this ended up making it into 2.1.0 since that recently got released.