revlog: register changelogv2 C implementation in parsers
This allows Python code to make use of the C implementation of the changelogv2
base operations when the C extensions are enabled.
The `format_version` values are now shared between the C and Python sides,
avoiding an additional translation for the selection of the format version to
use.
Differential Revision: https://phab.mercurial-scm.org/D12179
{
// Enforcing
"eqeqeq" : true, // true: Require triple equals (===) for comparison
"forin" : true, // true: Require filtering for..in loops with obj.hasOwnProperty()
"freeze" : true, // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
"nonbsp" : true, // true: Prohibit "non-breaking whitespace" characters.
"undef" : true, // true: Require all non-global variables to be declared (prevents global leaks)
// Environments
"browser" : true // Web Browser (window, document, etc)
}