Remove broken MSVC support
MSVC compilation has been broken since at least 1e417b72 ("All remaining files in src/common belong to the event loop.") deleted src/common/Makefile.nmake in 2018.
MSVC compilation has been broken since at least 1e417b72 ("All remaining files in src/common belong to the event loop.") deleted src/common/Makefile.nmake in 2018.