* lisp/mail/footnote.el: Add TEXT and POINTERS together

Rather than adding POINTERS and TEXT separately to footnote--markers-alist,
add them together, so we don't need footnote--first-text-marker because
the TEXT part is never nil.

(footnote--insert-numbered-footnote): Return marker.
(footnote--insert-text-marker, footnote--insert-pointer-marker):
Delete functions.
(footnote--insert-markers): New function to replace them.
(footnote--insert-footnote): Adjust accordingly.
Simplify pointless `unless`.
(footnote--first-text-marker): Remove.  Replace all calls by
(cadr (car footnote--markers-alist)) or just footnote--markers-alist.
1 job for master in 77 minutes and 33 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #1620
test-all

01:17:33

 
Name Stage Failure
failed
test-all Test
Makefile:315: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:290: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:963: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1