Tags: patch

The new mode line right alignment requires setting `mode-line-format` to
a list that contains (as in `memq`) the symbol
`mode-line-format-right-align`.  This is a bit brittle, and currently
`eldoc-minibuffer-message` modifies `mode-line-format` in a way that
happens to break `mode-line-format-right-align`.  To see that, set
`mode-line-format` to '("" mode-line-format-right-align "foo bar") and
then type `M-: (list`.  Now ElDoc info appears on the mode line, but
"bar" is no longer visible.

This patch makes ElDoc modify `mode-line-format` in an equivalent way
that avoids messing with `mode-line-format-right-align`.