Ignore pending_signals when checking for quits.

Ignore pending_signals when checking for quits.

pending_signals is often set if no quit is pending.  This results in
bugs in module code if the module returns but no quit is actually
pending.

* src/emacs-module.c (module_should_quit): Use QUITP macro to check
whether the caller should quit.

* src/eval.c: Remove obsolete comment.