[analyzer] Remove constraints on dead symbols as part of removeDeadBindings.

Previously, we'd just keep constraints around forever, which means we'd
never be able to merge paths that differed only in constraints on dead

Because we now allow constraints on symbolic expressions, not just single
symbols, this requires changing SymExpr::symbol_iterator to include
intermediate symbol nodes in its traversal, not just the SymbolData leaf

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@163444 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed