Do not perform trampoline optimization at speed 3 on function if their
name is not unique inside the compilation unit. Note that the
function can still be redefined in any other way therefore this is a
mitigation.
* lisp/emacs-lisp/comp.el (comp-func-unique-in-cu-p): New
predicate.
(comp-call-optim-form-call): Perform trampoline optimization
for named functions only if they are unique within the current
compilation unit.