Error code reporting in .bat files is broken in Windows.

For backwards compatibility, defaults to ON. You can turn it OFF to skip
building and installing static libbson. ENABLE_TESTS must also be OFF.

Ensure that the regex option flags "ilmsux" are stored in sorted order,
even when passed to bson_append_regex.

By the time JSONSL checks if a u-escape value is less than 0xDC00, it
already knows it is greater than 0xD7FF.

A change in the Extended JSON Spec.

Extended JSON spec prohibits it, only {"$date": "2017-06-07T12:34:45"}
or {"$date": {"$numberLong": "12345"}} are allowed.

Implement the "degenerate_extjson" portion of the tests.

Don't escape "/". Use hex code, not decimal, for u-escapes.