This causes warnings on newer GCC and Clang versions that enable
-Wexpansion-to-defined by default.

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.