Analyzer Core: In checkDeadSymbols checker callback, provide the state in...

Analyzer Core: In checkDeadSymbols checker callback, provide the state in which the symbols are not yet deleted so that checkers could inspect them. Since we are now always creating a transition in ProcessStmt(), remove the logic for adding a transition when none was generated. TODO: the extra transitions will have to be removed; more cleanups; a checker that tests teh new fucntionality.

llvm-svn: 137273