[WINNT] macro definition

(xposting on build and test ML)

Hi,

I have some failures on the teeks machines (eg.
teeks99-09-p-win2012R2-64on64) that I am not able to reproduce. The test
that fails is "test-timeout-fail" and checks for a timeout.

I recently introduced this for boost.test, but the feature relies on this

#  if defined(_MSC_VER) && (_WIN32_WINNT >= 0x0501) /* WinXP */

after the inclusion of "<windows.h>".

My guess is that _WIN32_WINNT is not defined.

What is the good way of defining this? Should this definition go to the
Jamfile? how does this definition propagate to projects that are
themselves defining this macro?

My understanding is that it is safe to define it to the lowest supported
value, and it will remain ABI compatible with new versions of kernel32.dll.

Any advices welcome,

Thanks!
Raffi