org-do-emphasis-faces: Never treat closing marker as next opening marker
* lisp/org.el (org-do-emphasis-faces): Make sure that we never match
ending marker of an emphasis as a beginning marker of another
emphasis. For example, in "(~-~) test (~+~)" "~) test (~" is a valid
code match unless we move point to the end the first code emphasis
completely during parsing.
Fixes https://orgmode.org/list/87fsujp7mc.fsf@web.de