work around hang when deleting a TempAllocatorMalloc on Windows

src/main/java/com/github/stephengold/joltjni/TempAllocatorMalloc.java

@@ -38,7 +38,25 @@ public TempAllocatorMalloc() {
         setVirtualAddress(allocatorVa, true);
     }
     // *************************************************************************
+    // TempAllocator methods
+
+    /**
+     * Unassign the assigned native object, assuming there is one. Free the
+     * native object if the current allocator owns it.
+     */
+    @Override
+    public void close() {
+        if (ownsNativeObject()) {
+            long allocatorVa = va();
+            free(allocatorVa);
+        }
+
+        unassignNativeObject();
+    }
+    // *************************************************************************
     // private methods
 
     native private static long create();
+
+    native private static void free(long allocatorVa);
 }

src/main/native/glue/TempAllocatorMalloc.cpp

@@ -39,3 +39,18 @@ JNIEXPORT jlong JNICALL Java_com_github_stephengold_joltjni_TempAllocatorMalloc_
     NonCopyable * const pResult = new TempAllocatorMalloc();
     return reinterpret_cast<jlong> (pResult);
 }
+
+/*
+ * Class:     com_github_stephengold_joltjni_TempAllocatorMalloc
+ * Method:    free
+ * Signature: (J)V
+ */
+JNIEXPORT void JNICALL Java_com_github_stephengold_joltjni_TempAllocatorMalloc_free
+  (JNIEnv *, jclass, jlong allocatorVa) {
+#ifndef WIN32
+    // Attempting to delete a TempAllocatorMalloc on Windows causes deadlock!
+    const NonCopyable * const pAllocator
+            = reinterpret_cast<NonCopyable *> (allocatorVa);
+    delete pAllocator;
+#endif
+}