Fix ./configure for Mac and Windows

Author: sfiera

build/lib

@@ -63,9 +63,13 @@ MAC = cfg.Distro(
 
 WIN = cfg.Distro(
     name="win",
-    packages={},
+    packages={
+        "ninja":
+        "https://github.com/ninja-build/ninja/releases/download/v1.10.2/ninja-win.zip:ninja.exe",
+        "gn": "https://chrome-infra-packages.appspot.com/dl/gn/gn/windows-amd64/+/latest:gn.exe",
+    },
     sources=[],
-    install="",
+    install="[download from]".split(),
     update=None,
     add_key=None,
 )