Remove unused Python local variables.

modules/mono/build_scripts/solution_builder.py

@@ -8,9 +8,6 @@ def find_dotnet_cli():
     import os.path
 
     if os.name == "nt":
-        windows_exts = os.environ["PATHEXT"]
-        windows_exts = windows_exts.split(os.pathsep) if windows_exts else []
-
         for hint_dir in os.environ["PATH"].split(os.pathsep):
             hint_dir = hint_dir.strip('"')
             hint_path = os.path.join(hint_dir, "dotnet")