sslutil: fix names of variables containing minimum protocol strings
When working in this module, I found it very confusing that "protocol" as a
variable name could mean either "minimum protocol string" or an exact version
(as a string or ssl.PROTOCOL_* value). This patch prefixes variables of the
former type with "minimum".
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}