revlog-compression: use zstd by default (if available)
As see in changeset
bb271ec2fbfb, zstd is 20% to 50% faster for reading and
writing.
Use take advantage of the new config behavior to try zstd by default, falling
back to zlib is zstd is not available on that plateform.
Differential Revision: https://phab.mercurial-scm.org/D10326
{
// 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)
}