chore(util): remove dead file

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/util/interruptable_ptr.h

@@ -1,60 +0,0 @@
-/*
-Copyright (c) 2013 Microsoft Corporation. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-
-Author: Leonardo de Moura
-*/
-#pragma once
-#include "util/thread.h"
-
-namespace lean {
-/**
-    \brief Auxiliary class that wraps a pointer to a type that has a
-    set_interrupt method. The set_interrupt can be invoked from a different
-    execution thread. To prevent race conditions, we use mutex whenever we
-    reset the pointer, or invoke the set_interrupt method.
-
-    The common usage scenario is:
-    1) Thread A creates creates a new object Obj and invokes set(Obj)
-    2) Thread B invokes set_interrupt, which invokes Obj->set_interrupt
-    3) Thread A invokes set(nullptr) before deleting Obj.
-
-    We use the mutex to avoid a race condition in 2&3.
-*/
-template<typename T>
-class interruptable_ptr {
-    T *   m_ptr;
-    mutex m_mutex;
-public:
-    interruptable_ptr():m_ptr(nullptr) {}
-
-    T * set(T * ptr) {
-        lock_guard<mutex> lock(m_mutex);
-        T * old = m_ptr;
-        m_ptr = ptr;
-        return old;
-    }
-
-    void set_interrupt(bool flag) {
-        lock_guard<mutex> lock(m_mutex);
-        if (m_ptr)
-            m_ptr->set_interrupt(flag);
-    }
-};
-
-/**
-   \brief Auxiliary class for setting/resetting  a interruptable_ptr.
-*/
-template<typename T>
-struct scoped_set_interruptable_ptr {
-    interruptable_ptr<T> & m_ptr;
-    T *                    m_old_p;
-public:
-    scoped_set_interruptable_ptr(interruptable_ptr<T> & ptr, T * p):m_ptr(ptr) {
-        m_old_p = m_ptr.set(p);
-    }
-    ~scoped_set_interruptable_ptr() {
-        m_ptr.set(m_old_p);
-    }
-};
-}