...to make it more straightforward to fix blunder as in
a88b2d84 "Resolves: fdo#81039 crash on adding
new macro library."

Conceivably, instances of heap_ptr could legitimately be created only for ctor/
dtor effect, but then again uses of heap_ptr should arguably be replaced with
std::unique_ptr anyway.

Change-Id: I9c765b8d265f3c26d459ec276e335eeebc8fee91