* upstream-jsoncpp:
  jsoncpp 2022-01-12 (42e892d9)

* upstream-jsoncpp:
  jsoncpp 2020-09-25 (9059f5ca)

Revert the part of commit 209daa20b2 (Code style: add missed explicit
'this->', 2021-01-05, v3.20.0-rc1~213^2) that updated third-party code.

CMake uses explicit 'this->' style. Using custom clang-tidy check we can
detect and fix places where 'this->' was missed.

In particular, fix the `isfinite` definition.

Clang's ubsan (-fsanitize=undefined) reports:

    runtime error: negation of -9223372036854775808 cannot be represented in
    type 'Json::Value::LargestInt' (aka 'long'); cast to an unsigned type to
    negate this value to itself

Follow its advice and update the code to remove the explicit negation.

Some Clang versions warn with `-Wdocumentation-unknown-command` about
the `\internal` and `\snippet` command tag names.

The scanbuild analysis cannot see that decodeUnicodeEscapeSequence
either initializes the `unicode` argument or returns `false` such
that the code following it runs only if `unicode` is initialized.
Add an explicit initialization to pacify it.

* upstream-jsoncpp:
  jsoncpp 2017-08-27 (4cfae897)