visualcpp toolchain: change compiler/linker flags

with these flags visualcpp should behave more like the gcc toolchain

c:
- produce debug information
- optimize for speed instead of disabling optimization
- use non-debug version of Microsoft's C library
- remove unused and unnecessary macro definitions

cxx:
- separate C and C++ (#1594)
- specify kind of exception handling (see warning C4530)

linker:
- produce debug information
- disable incremental linking and re-enable optimizations