Correct TRASH() macro usage

TRASH was mapped to TRASH_FREE and was supposed to be used for memory
that should not be accessed anymore, while TRASH_ALLOC() is to be
used for uninitialized but to-be-used memory.

But sometimes TRASH() was used in the latter sense.

Remove TRASH() macro, always use explicit TRASH_ALLOC() or TRASH_FREE().

sql/opt_range.cc

@@ -2651,7 +2651,7 @@ public:
   /* Table read plans are allocated on MEM_ROOT and are never deleted */
   static void *operator new(size_t size, MEM_ROOT *mem_root)
   { return (void*) alloc_root(mem_root, (uint) size); }
-  static void operator delete(void *ptr,size_t size) { TRASH(ptr, size); }
+  static void operator delete(void *ptr,size_t size) { TRASH_FREE(ptr, size); }
   static void operator delete(void *ptr, MEM_ROOT *mem_root) { /* Never called */ }
   virtual ~TABLE_READ_PLAN() {}               /* Remove gcc warning */