When QSharedPointer is created with no user-specified custom deleter,
instead of storing a pointer in ExternalRefCount::destroyer to a
static function which, in turn, calls normalDeleter<T> indirectly (via
another function pointer), specialise the CustomDeleter class and make
it not store the pointer, but instead do the deleting directly.
The benefits are:
- the QSharedPointer's private data is smaller
- there is no double-indirection via indirect jumps to the actual
deleter
Change-Id: Ice5653c144912efb1226e432267a047b9799aaca
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
267b1a791d