Fix a critical bug where access paths were walked in the wrong order.
Fix a critical bug where access paths were walked in the wrong order.

This was apparently never a problem before since I was never issuing
queries for paths with length greater than 1 (or I was getting very
lucky).

Switched from a foldr to a foldl'

wangxiayang/llvm-analysis,travitch/llvm-analysis,travitch/llvm-analysis,wangxiayang/llvm-analysis