The lexical scope counting added by commit v3.2.0-rc1~332^2~1 (Track
nested loop levels in CMake language with a stack of counters,
2014-11-18) forgot to account for scopes popped by error messages about
unclosed scopes. Teach the error handler to pop the lexical scope it
reports as unclosed. Re-order the lexical scope RAII object to be
inside the variable scope RAII object scope so that the lexical scope
is fully closed before we check assertions about variable scopes.
Extend the RunCMake.Syntax test with a case covering this.
Brad King