[analyzer] Extend IdenticalExprChecker to check logical and bitwise expressions.

IdenticalExprChecker now warns if any expressions in a logical or bitwise
chain (&&, ||, &, |, or ^) are the same. Unlike the previous patch, this
actually checks all subexpressions against each other (an O(N^2) operation,
but N is likely to be small).

Patch by Daniel Fahlgren!

llvm-svn: 201702