Enhance SimpleSValuator::EvalBinOpNN to recognize the trivial case

where we are comparing a symbolic value against itself, regardless of
the nature of that symbolic value.

This enhancement identified a case where RegionStoreManager is not
correctly symbolicating the values of the pointees of parameters.  The
failing test is now in 'test/Analysis/misc-ps-region-store.m', with
that test file now (temporarily) marked XFAIL.

llvm-svn: 75521