Reorganizing source code. Created util dir

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

lib/stack.h

@@ -1,50 +0,0 @@
-/*++
-Copyright (c) 2007 Microsoft Corporation
-
-Module Name:
-
-    stack.h
-
-Abstract:
-    Low level stack (aka stack-based allocator).
-
-Author:
-
-    Leonardo (leonardo) 2011-02-27
-
-Notes:
-
---*/
-#ifndef _STACK_H_
-#define _STACK_H_
-
-#include"page.h"
-#include"debug.h"
-
-class stack {
-    char *   m_curr_page;
-    char *   m_curr_ptr;     //!< Next free space in the current page.
-    char *   m_curr_end_ptr; //!< Point to the end of the current page.
-    char *   m_free_pages;
-    void store_mark(size_t m);
-    void store_mark(void * ptr, bool external);
-    size_t top_mark() const;
-    void allocate_page(size_t mark);
-    void * allocate_small(size_t size, bool external);
-    void * allocate_big(size_t size);
-public:
-    stack();
-    ~stack();
-    void * allocate(size_t size) { return size < DEFAULT_PAGE_SIZE ? allocate_small(size, false) : allocate_big(size); }
-    void deallocate();
-    bool empty() const { return reinterpret_cast<size_t*>(m_curr_ptr)[-1] == 0; }
-    void * top() const;
-    void reset();
-    template<typename T>
-    void deallocate(T * ptr) { SASSERT(ptr == top()); ptr->~T(); deallocate(); }
-};
-
-inline void * operator new(size_t s, stack & r) { return r.allocate(s); }
-inline void operator delete(void * ptr, stack & r) { SASSERT(ptr == r.top()); r.deallocate(); }
-
-#endif