Don't try freeing the context in ReleaseThreadCtx

Unfortunately on certain systems, the TLS callback is called in a restricted
context, and isn't allowed to access certain messaging sub-systems. Such sub-
systems may be used if the thread's context is freed, in turn freeing the
device, which it tries to close.

Ideally, the app shouldn't have tried to destroy a context while it was still
current on a thread, or even leave a context current on a thread that's being
destroyed,. So for now, release the context ref and print an ERR that it might
be leaked.

Alc/ALc.c

@@ -2376,23 +2376,23 @@ static void ReleaseContext(ALCcontext *context, ALCdevice *device)
 
 void ALCcontext_IncRef(ALCcontext *context)
 {
-    uint ref;
-    ref = IncrementRef(&context->ref);
+    uint ref = IncrementRef(&context->ref);
     TRACEREF("%p increasing refcount to %u\n", context, ref);
 }
 
 void ALCcontext_DecRef(ALCcontext *context)
 {
-    uint ref;
-    ref = DecrementRef(&context->ref);
+    uint ref = DecrementRef(&context->ref);
     TRACEREF("%p decreasing refcount to %u\n", context, ref);
     if(ref == 0) FreeContext(context);
 }
 
 static void ReleaseThreadCtx(void *ptr)
 {
-    WARN("%p current for thread being destroyed\n", ptr);
-    ALCcontext_DecRef(ptr);
+    ALCcontext *context = ptr;
+    uint ref = DecrementRef(&context->ref);
+    TRACEREF("%p decreasing refcount to %u\n", context, ref);
+    ERR("Context %p current for thread being destroyed, possible leak!\n", context);
 }
 
 /* VerifyContext