- forces c++DBUG='-DFULLDEBUG -g -O0' for the compilation, to allow
localized debugging during development without file editing and
while retaining the WM_COMPILE_OPTION (eg, Opt)
Note that switching between 'wmake' and 'wmake -debug' will not
cause existing targets to be rebuilt. As before, these are driven by
the dependencies. An intermediate wclean may thus be required.