Fix memory ownership in the NeonEmitter by using values instead of pointers (smart...

Fix memory ownership in the NeonEmitter by using values instead of pointers (smart or otherwise)

Improvement to the memory leak fix in 244196.

Address validity is required for the Intrinsic objects, but since the
collections only ever grow (no elements are removed), deque provides
sufficient guarantees (that the objects will never be reallocated/moved
around) for this use case.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@244241 91177308-0d34-0410-b5e6-96231b3b80d8