Update Android port

Update Android port

* java/org/gnu/emacs/EmacsContextMenu.java (display): Return
false if the list of menu buttons is empty, lest Android cease
displaying menus on the assumption that Emacs is defective.

* java/org/gnu/emacs/EmacsView.java (popupMenu): Likewise.

* src/fns.c (sort_list): Render sentence motion commands
functional within commentary

* src/sfntfont.c (sfntfont_list_family): Sort and deduplicate
the returned family list and make it a list of symbols.
(syms_of_sfntfont) <Qstring_lessp>: New defsym.