Fix for two defects as follows:

- The IO mapping traverser was not setting inVisit, and would skip some AST nodes.
  Depending on the order of nodes, this could have prevented the binding from
  showing up in the generated SPIR-V.

- If a uniform array was flattened, each of the flattened scalars from the array
  is still a (now-scalar) uniform.  It was being converted to a temporary.