Make CATCH_BREAK_INTO_DEBUGGER be user-configurable

[khyperia]

Unfortunately, the project I work on supports platforms under NDA, and so I can't upstream the fixes here.

(It'd be really nice if all platform configuration macros like this were externally configurable! But just this one is the one we need right now.)

[khyperia]

The test failure is Error: retrieving gpg key timed out., not sure how to retrigger tests

[horenmar]

AFAIK only accounts with access to the repo are allowed to rerun Travis tests.

Anyway, the change looks reasonable enough, but I'd like to also see it added to the documentation. (See docs/contributing.md how to properly add a "introduced in" placeholder)

[codecov]

Codecov Report

Merging #1846 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1846   +/-   ##
=======================================
  Coverage   86.27%   86.27%           
=======================================
  Files         131      131           
  Lines        3888     3888           
=======================================
  Hits         3354     3354           
  Misses        534      534

[khyperia]

Let me know if that's what you were thinking of with documentation!

[horenmar]

Thanks. The documentation was good enough but I noticed that it was a subheading of "Disabling Exceptions", so I pulled it out and rewrote slightly.