Trace loads and stores as they happen (stores were being

Trace loads and stores as they happen (stores were being
remembered in valuesStoredInFunction, but never traced at function return,
and that's too late to be finding the error anyway).
Stores trace both the value and the address being stored to,
but after some experience I think only values should be traced.
The pointer hash table just fills up far too quickly if every
store address were traced.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7169 91177308-0d34-0410-b5e6-96231b3b80d8