Static analysis unearther a bunch of uninitialised variables and
members, and this patch addresses the problem. In all cases these
omissions seem benign in the end, but at least fixing them means less
false positives next time round.
Without this declaration, new clangs will complain about this value
being unused. It has no explicit use in the codebase, but it can be
useful to turn on all debugging flags while in a debugger to greatly
increase simulator verbosity.
At the same time, rename the trace flags to debug flags since they
have broader usage than simply tracing. This means that
--trace-flags is now --debug-flags and --trace-help is now --debug-help