servo: Merge #14303 - Use msvc toolchain when in Visual Studio env (from upsuper:triple-msvc); r=bholley

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r? @bholley

Source-Repo: https://github.com/servo/servo
Source-Revision: e97804986ad259083981db7d4f7995d822d693b5

servo/python/servo/command_base.py

@@ -107,7 +107,8 @@ def host_triple():
     elif os_type == "android":
         os_type = "linux-androideabi"
     elif os_type == "windows":
-        if os.getenv("MSYSTEM") is None:
+        # If we are in a Visual Studio environment, use msvc
+        if os.getenv("VSInstallDir") is not None:
             os_type = "pc-windows-msvc"
         else:
             os_type = "pc-windows-gnu"