windows.h defines exception_code as a macro, which conflicts with our
use of the identifier in exception records. It appears that this
particular include of windows.h is not needed, so instead of undefining
the macro, I simply delete the include. Build tested with MSVC 2013.

BUG=
R=mark@chromium.org

Review URL: https://codereview.chromium.org/1579623004 .

Patch from Pavel Labath <labath@google.com>.