[analyzer] Address Jordan’s review of r177138 (a micro optimization)
[analyzer] BugReporterVisitors: handle the case where a ternary operator is wrapped in a cast.
[analyzer] Use isLiveRegion to determine when SymbolRegionValue is dead.

Fixes a FIXME, improves dead symbol collection, suppresses a false positive,
which resulted from reusing the same symbol twice for simulation of 2 calls to the same function.

Fixing this lead to 2 possible false negatives in CString checker. Since the checker is still alpha and
the solution will not require revert of this commit, move the tests to a FIXME section.
[analyzer] Address a TODO in the StreamChecker; otherwise the output is non-deterministic.