replace VS 16 2019 generator with NMake Makefiles
{% set config_extra = "--enable-cuda" %} # [linux and cuda_compiler_version != "None"]
{% set config_extra = "--disable-cuda" %} # [not (linux and cuda_compiler_version != "None")]
-{% set generator = "Visual Studio 16 2019" %} # [win]
+{% set generator = "NMake Makefiles" %} # [win]
{% set generator = "Ninja" %} # [not win]
{% set cmake_extra = "-A x64" %} # [win]
