tsan: fix the following compiler warning
sanitizer_common_interceptors.inc:1142:53: warning: invoking macro INTERCEPTOR argument 3: empty macro arguments are undefined in ISO C90 and ISO C++98 [enabled by default]
Enable building LTO on WIN32.

Enable building the LTO library (.lib and.dll) and llvm-lto.exe on Windows with
MSVC and Mingw as well as re-enabling the associated test.

Patch by Greg Bedwell!