fix: Try fix weak reference tests under lto=thin (#3865)

unit-tests/native/src/test/scala/org/scalanative/testsuite/javalib/lang/ref/WeakReferenceTest.scala

@@ -28,22 +28,22 @@ class WeakReferenceTest {
     )
   }
 
-  @noinline def allocWeakRef(
+  @nooptimize @noinline def allocWeakRef(
       referenceQueue: ReferenceQueue[A]
   ): WeakReference[A] = {
     var a = A()
     val weakRef = new WeakReference(a, referenceQueue)
-    assertEquals("get() should return object reference", weakRef.get(), A())
+    assertEquals("get() should return object reference", weakRef.get(), a)
     a = null
     weakRef
   }
 
-  @noinline def allocSubclassedWeakRef(
+  @nooptimize @noinline def allocSubclassedWeakRef(
       referenceQueue: ReferenceQueue[A]
   ): SubclassedWeakRef[A] = {
     var a = A()
     val weakRef = new SubclassedWeakRef(a, referenceQueue)
-    assertEquals("get() should return object reference", weakRef.get(), A())
+    assertEquals("get() should return object reference", weakRef.get(), a)
     a = null
     weakRef
   }
@@ -54,7 +54,7 @@ class WeakReferenceTest {
       sys.env.contains("CI") && Platform.isWindows
     )
 
-    def assertEventuallyIsCollected(
+    @noinline def assertEventuallyIsCollected(
         clue: String,
         ref: WeakReference[_],
         deadline: Long
@@ -74,8 +74,8 @@ class WeakReferenceTest {
             locally {
               val _ = Seq.fill(1000)(new Object {})
             }
-            Thread.sleep(200)
             System.gc()
+            Thread.sleep(200)
             assertEventuallyIsCollected(clue, ref, deadline)
           } else {
             fail(