Added sql_alloc.h

- Moved declaration of Sql_alloc from Sql_list.h as they are independent
  structures.

sql/sql_alloc.h

@@ -0,0 +1,54 @@
+#ifndef SQL_ALLOC_INCLUDED
+#define SQL_ALLOC_INCLUDED
+/* Copyright (c) 2000, 2012, Oracle and/or its affiliates.
+   Copyright (c) 2017, MariaDB AB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+
+#include <my_sys.h>                    /* alloc_root, MEM_ROOT, TRASH */
+
+THD *thd_get_current_thd();
+
+/* mysql standard class memory allocator */
+
+class Sql_alloc
+{
+public:
+  static void *operator new(size_t size) throw ()
+  {
+    return thd_alloc(thd_get_current_thd(), size);
+  }
+  static void *operator new[](size_t size) throw ()
+  {
+    return thd_alloc(thd_get_current_thd(), size);
+  }
+  static void *operator new[](size_t size, MEM_ROOT *mem_root) throw ()
+  { return alloc_root(mem_root, size); }
+  static void *operator new(size_t size, MEM_ROOT *mem_root) throw ()
+  { return alloc_root(mem_root, size); }
+  static void operator delete(void *ptr, size_t size) { TRASH(ptr, size); }
+  static void operator delete(void *ptr, MEM_ROOT *mem_root)
+  { /* never called */ }
+  static void operator delete[](void *ptr, MEM_ROOT *mem_root)
+  { /* never called */ }
+  static void operator delete[](void *ptr, size_t size) { TRASH(ptr, size); }
+#ifdef HAVE_valgrind
+  bool dummy_for_valgrind;
+  inline Sql_alloc() :dummy_for_valgrind(0) {}
+#else
+  inline Sql_alloc() {}
+#endif
+  inline ~Sql_alloc() {}
+};
+#endif /* SQL_ALLOC_INCLUDED */