[freetds] Cmake support added

[Frediano Ziglio]

I finally found some time to finish my cmake patch

See
https://gitorious.org/~freddy77/freetds/mars-freetds/commit/2b3f4b8e58193605862d2ffbb185a1ad040b6be9for
notes.

It does not completely work for Unix but is very useful for Windows users
as it can generated files for more used IDEs. It can be used even with
MingW (even cross one)

Frediano