* Add libbacktrace to depends
This is currently only useful to extract symbols. It fails to gather
stacktraces when compiled with MinGW, so we can only use it to get symbol
information from a stack trace which we gathered outside of libbacktrace.
* Add -mbig-obj to CXXFLAGS for MinGW builds
* Implement stacktraces for C++ exceptions
This is a hack and should only be used for debugging. It works by wrapping
the C++ ABI __wrap___cxa_allocate_exception. The wrapper records a backtrace
and stores it in a global map. Later the stacktrace can be retrieved with
GetExceptionStacktraceStr.
This commit also adds handlers to pretty print uncaught exceptions and
signals.
* Use GetPrettyExceptionStr for all unhandled exceptions
* Use --enable-stacktraces in CI for linux32/linux64
* Register exception translators to pretty print exceptions in unit tests
* Catch and print python exceptions when stopping nodes
Otherwise the code at the bottom is never executed when nodes crash,
leading to no output of debug.log files on Travis.
* Remove now unneeded/unused TestCrash methods
