fix(lua): cygwing compilation problem

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Merge branch 'master' of https://github.com/leodemoura/lean-leo
Merge branch 'master' of https://github.com/leodemoura/lean-leo
fix(cmake/Modules/CheckLuaNewstate.cc): compilation problem on cygwin

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>