In the Windows project file generator: update openssl and serf to the new dependency framework. The serf in-tree build needs openssl and we need openssl for running the tests.
* build/generator/gen_win.py (get_install_targets): Don't build a serf project if we use an installed serf. (get_external_project): Update check to avoid .serf_lib (get_win_defines): Use modern checks for library availability.
(get_win_includes, get_win_lib_dirs, get_win_libs): Remove hardcoded serf handling.
(write_serf_project_file): Use modern check.
* build/generator/gen_win_dependencies.py (GenDependenciesBase): Remove now unused variable. (find_libraries): Organize library find calls. Avoid 2 lines for openssl. (_find_zlib): Find ml from here. (_find_db): Remove unneeded '\n' (_find_openssl): New function. (_get_serf_version): Add include dir argument to allow probing in more locations. (_find_serf): Fill library object.