Revert "Don't try to free DLL on drop (rust-lang#1089)"

This reverts commit a6a928e.

Fix rust-lang CI

Author: arttet

src/windows/find_tools.rs

@@ -225,7 +225,7 @@ mod impl_ {
     use crate::windows::setup_config::SetupConfiguration;
     use crate::windows::vs_instances::{VsInstances, VswhereInstance};
     use crate::windows::windows_sys::{
-        GetMachineTypeAttributes, GetProcAddress, LoadLibraryA, UserEnabled, HMODULE,
+        FreeLibrary, GetMachineTypeAttributes, GetProcAddress, LoadLibraryA, UserEnabled, HMODULE,
         IMAGE_FILE_MACHINE_AMD64, MACHINE_ATTRIBUTES, S_OK,
     };
     use std::convert::TryFrom;
@@ -273,6 +273,12 @@ mod impl_ {
         }
     }
 
+    impl Drop for LibraryHandle {
+        fn drop(&mut self) {
+            unsafe { FreeLibrary(self.0) };
+        }
+    }
+
     type GetMachineTypeAttributesFuncType =
         unsafe extern "system" fn(u16, *mut MACHINE_ATTRIBUTES) -> i32;
     const _: () = {