- uses '-g -DFULLDEBUG' (like Debug), but with -O3 (like Opt).
This adds in debug symbols and FULLDEBUG code segments (good for
code development) but retains -O3 optimizations and code paths and
avoids the much slower -O0 associated with 'Debug'.
- add in central wmake/General/common/{c,c++}XXX tuning,
which helps reduce the number of nearly identical files
ENH: add support for wmake -debug-Og
