make it work on MS Windows

setup.py

@@ -1751,6 +1751,8 @@ def do_add_DLLs(prefix="lib", *dll_names: str) -> None:
         if client_ENABLED:
             # svg pixbuf loader:
             add_DLLs("rsvg", "croco")
+            # gio module and `xpra.net.libproxy`:
+            add_DLLs("proxy-1")
 
         if client_ENABLED or server_ENABLED:
             add_DLLs("qrencode")

xpra/net/libproxy.py

@@ -22,14 +22,20 @@
 A library for proxy configuration and autodetection.
 """
 
+import os
+
 from ctypes import POINTER, cast, c_void_p, c_char_p
 import ctypes.util
 
 
 def _load(name, *versions):
     for ver in versions:
+        if os.name == "nt":
+            libname = f"lib{name}-{ver}"
+        else:
+            libname = f"lib{name}.so.{ver}"
         try:
-            return ctypes.cdll.LoadLibrary(f'lib{name}.so.{ver}')
+            return ctypes.cdll.LoadLibrary(libname)
         except Exception:
             pass
     name_ver = ctypes.util.find_library(name)