- Change initializeResult(int) to initializeResult(bool) to avoid
implicit type conversion.
- Use EXIT_FAILURE and EXIT_SUCCESS instead of magic numbers.
- Remove the argument from shutdownResult(int); it was called with a
constant argument.
Backport of https://github.com/bitcoin/bitcoin/pull/9834
Co-authored-by: Jason B. Cox <contact@jasonbcox.com>