Windows build system fixes

setup.py

@@ -179,6 +179,7 @@ else:
         'z'
         ]
     
+    if not windows_check():
         dynamic_lib_extension = ".so"
         if osx_check():
             dynamic_lib_extension = ".dylib"
@@ -211,7 +212,7 @@ for source in _sources:
             break
 
 _ext_modules = []
-if not os.path.exists(os.path.join(sysconfig.get_config_var("LIBDIR"), "libtorrent-rasterbar.so.1")):
+if windows_check() or not os.path.exists(os.path.join(sysconfig.get_config_var("LIBDIR"), "libtorrent-rasterbar.so.1")):
     # There isn't a system libtorrent library, so let's build the one included with deluge
     libtorrent = Extension(
         'libtorrent',