Firmware BMP with ENABLE_DEBUG=1 will print WARN and INFO as before.
PC-Hosted BMPwill alway print to stderr. Warn is printed unconditional,
INFO, GDB, TARGET, DONGLE and WIRE will print if their appropriate bit in
cl_debuglevel is set via the -v verbose command line argument.
INFO will go to stdout with -t or -l.
This is will make debugging earier if this does happen, rather than
dereferencing the null pointer (or passing it to memcpy, or worse).
blackmagic PR #475
