make valgrind understand our memory pools

Annotate pools with valgrind macros so that it detects errors in pool
usage. Typically, we wish valgrind to detect a leak when the user fails
to call proper deallocation function.

* spot/misc/fixpool.hh, spot/misc/mspool.hh: here
* configure.ac: ensure that valgrind header exists
* tests/Makefile.am, tests/core/mempool.cc, tests/core/mempool.test,
  tests/core/.gitignore: add tests to ensure valgrind accurately detects
  leaks

spot/misc/mspool.hh

@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2011, 2013, 2015, 2016 Laboratoire de Recherche et
+// Copyright (C) 2011, 2013, 2015, 2016, 2018 Laboratoire de Recherche et
 // Developpement de l'Epita (LRDE)
 //
 // This file is part of Spot, a model checking library.
@@ -20,10 +20,11 @@
 #pragma once
 
 #include <spot/misc/common.hh>
-#include <spot/misc/hash.hh>
-#include <new>
-#include <cstddef>
-#include <cstdlib>
+#include <unordered_map>
+
+#if SPOT_DEBUG && defined(HAVE_VALGRIND_MEMCHECK_H)
+#include <valgrind/memcheck.h>
+#endif
 
 namespace spot
 {
@@ -69,6 +70,12 @@ namespace spot
       if (f)
         {
           block_* first = f;
+#if SPOT_DEBUG && defined(HAVE_VALGRIND_MEMCHECK_H)
+          VALGRIND_MALLOCLIKE_BLOCK(f, size, 0, false);
+          // field f->next is initialized: prevents valgrind from complaining
+          // about jumps depending on uninitialized memory
+          VALGRIND_MAKE_MEM_DEFINED(f, sizeof(block_*));
+#endif
           f = f->next;
           return first;
         }
@@ -92,6 +99,9 @@ namespace spot
 
       void* res = free_start_;
       free_start_ += size;
+#if SPOT_DEBUG && defined(HAVE_VALGRIND_MEMCHECK_H)
+      VALGRIND_MALLOCLIKE_BLOCK(res, size, 0, false);
+#endif
       return res;
     }
 
@@ -113,6 +123,9 @@ namespace spot
       block_*& f = freelist_[size];
       b->next = f;
       f = b;
+#if SPOT_DEBUG && defined(HAVE_VALGRIND_MEMCHECK_H)
+      VALGRIND_FREELIKE_BLOCK(ptr, 0);
+#endif
     }
 
   private: