PATCH: Conditionalize `doc-view-mode'

[Michael Sperber]

This patch unbreaks PDF viewing on XEmacs. (Well, partly, see next
patch.) If somebody could apply it, that would be much appreciated.

[Katsumi Yamaoka]

Post by Michael Sperber
This patch unbreaks PDF viewing on XEmacs. (Well, partly, see next
patch.) If somebody could apply it, that would be much appreciated.

This is necessary for XEmacs to work. I'll install it in Gnus
and Emacs git masters. Thanks.