(if (and (featurep 'xemacs) blah) not optimized anymore

[Dan Nicolaescu]

Byte compiling this:

(if (and (featurep 'xemacs) blah)
    (foo))

with emacs-22.1 does not result in any warning, doing it with the
emacs from trunk results in this:

In end of data:
foo.el:2:11:Warning: the function `foo' is not known to be defined.

Any idea what went wrong?