proper executable files for Windows;

--- a/src/Pure/Tools/dotnet_setup.scala	Sun Nov 06 12:20:38 2022 +0100
+++ b/src/Pure/Tools/dotnet_setup.scala	Sun Nov 06 12:54:46 2022 +0100
@@ -137,6 +137,9 @@
               " -NoPath"
           progress.bash(script, echo = verbose,
             cwd = if (dry_run) null else component_dir.file).check
+          for (exe <- File.find_files(platform_dir.file, pred = _.getName.endsWith(".exe"))) {
+            File.set_executable(File.path(exe), true)
+          }
         }
       }
     }