llexception_test.cpp is about discovering appropriate infrastructure to get
good information from the LLTHROW() and LOG_UNHANDLED_EXCEPTION() mechanism.
But we didn't before have a test that actually exercises them. Now we do.
llexception_test.cpp is an unusual test source in that it need not be verified
on every build, so its invocation in indra/llcommon/CMakeLists.txt is
commented out with that remark. Its purpose is to help a developer decide what
base class(es) to use for LLException, how to throw and how to catch.
Our current conclusions are written up as comments in llexception_test.cpp.
Added CRASH_ON_UNHANDLED_EXCEPTION() and LOG_UNHANDLED_EXCEPTION() macros to
llexception.h -- macros to log __FILE__, __LINE__ and __PRETTY_FUNCTION__ of
the catch site. These invoke functions in llexception.cpp so we don't need to
#include llerror.h for every possible catch site.
Nat Goodspeed