Win32: tweak the SSL certificate validation override to avoid hitting the wire for URL based objects and revocation checks.
The primary purpose of this callback is to resolve SVN_AUTH_SSL_UNKNOWNCA failures using CryptoAPI and Windows local certificate stores. To do so, we should be fine with just using the immediately available data on the local machine.
Doing the opposite of that appears to be troublesome, as always connecting to remote CRL and OCSP endpoints can result in spurious errors or significant (user-reported) network stalls caused by timeouts if the endpoints are inaccessible or unreliable.
* subversion/libsvn_subr/win32_crypto.c (windows_validate_certificate): Use the CERT_CHAIN_CACHE_ONLY_URL_RETRIEVAL and CERT_CHAIN_REVOCATION_CHECK_CACHE_ONLY flags when preparing the certificate chain. Ignore errors in obtaining valid revocation information when verifying the chain, as they could be induced by the new cache-only behavior.