Appeyor: added msbuild, disabled MSYS2 and Cygwin.
Appeyor: added msbuild, disabled MSYS2 and Cygwin.

Added msbuild to build matrix. Because MSYS2 and Cygwin don't have a proper build yet and they both take long to execute, they are disabled for now.

ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz