First-class support for sanitizers

Description When running tests in continuous integration, it is rather common to use sanitizers (ubsan, asan, tsan, etc.). It would be nice if Catch2 reported errors as usual and logged the information that it generally logs when a test fails, such as the seed that was passed to the command line if any.

In libc++ at least, the sanitizers have a public API: https://github.com/llvm-mirror/compiler-rt/blob/release_36/include/sanitizer/common_interface_defs.h

It might be possible to do something with __sanitizer_set_death_callback or the other sanitizer-specific callbacks that can be found in the other headers in the same directory.