Remove LatencyPriorityQueue::dump because it relies on an implicit copy ctor...

Remove LatencyPriorityQueue::dump because it relies on an implicit copy ctor which is deprecated in C++11 (due to the presence of a user-declare dtor in the base class)

This type could be made copyable (= default a protected copy ctor in the
base class, and preferably make the derived class final to avoid risks
of providing a slicing copy operation to further derived classes) but it
seemed easier to avoid that complexity for a dump function that I assume
(by symmetry with ResourcePriorityQueue's dump, which was actively
buggy) not often used.

llvm-svn: 231133