cccl: Ability to enable compiler optimization.

MSVC has a '-O2' compiler optimization flag which makes code run
fast and is the recommended option for released code. For e.g.,
running "./tests/ovstest.exe test-cmap benchmark 1000000 3 1"
shows a 3x improvement for some cmap micro-benchmarks.

In the Visual Studio world, there is a concept of "release" build
(fast code, harder to debug) and a "debug" build (easier to debug).
The IDE provides this option and the IDE users expect something similar
for command line build.

So this commit, introduces a "--with-debug" configure option for Windows
and does not use '-O2' as a compiler option when specified. This can
be extended further if there are more compiler options that distinguish
a "release" build vs "debug" build.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Saurabh Shah <ssaurabh@vmware.com>