util.xml: Deduplicate handlers for restricted XML
Makes the code more like util.xmppstream, allowing easier comparisons if
we ever need to apply fixes in the future.
[v3_extensions]
basicConstraints = CA:TRUE
subjectAltName = @subject_alternative_name
[subject_alternative_name]
DNS.0 = localhost
otherName.0 = 1.3.6.1.5.5.7.8.7;IA5STRING:_xmpp-client.localhost
otherName.1 = 1.3.6.1.5.5.7.8.7;IA5STRING:_xmpp-server.localhost
otherName.2 = 1.3.6.1.5.5.7.8.5;FORMAT:UTF8,UTF8:localhost
[distinguished_name]
countryName = GB
organizationName = Prosody IM
organizationalUnitName = https://prosody.im/doc/certificates
commonName = Example certificate
[req]
prompt = no
x509_extensions = v3_extensions
req_extensions = v3_extensions
distinguished_name = distinguished_name