Watchpoint set on stack variable can point to the wrong thing

[gsmcmullin]

Stack local variables may now be added to the variable watch view, but double clicking on them in the expanded call stack view. This works well for inspection and assignments, but when setting a watchpoint on the variable object things can go wrong.

When the user requests a watchpoint on a variable object, we ask GDB for the expression for the object with -var-info-path-expression <path>, and then set a watchpoint on this expression with -break-watch <expr>. This expression may not be evaluated in the context in which it was created.