`WIN32_LEAN_AND_MEAN` prevents "rarely-used" headers from being pulled in. This
significantly reduced preprocessor pressure, speeding up compile. It also
reduces the amount of cruft pulled in by the Windows.h.
`NOMINMAX` ensures that the `min` and `max` macros are not defined. These
macros collide with the use of `min` and `max` from C++ in certain cases: e.g.
`std::limits<T>`.
This patch is for libswiftCore.lib, linking with the library set of Visual Studio 2015. Clang with the option -fms-extension is used to build this port.
This is the approved subpatch of a large patch.