Crash of 4.2.0-dev-1

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

I presume of 4.2.0 also.  Reproduce as follows:

(1) Create a file "kshtest" in a directory in fpath.  This file should NOT
define the function "kshtest", that is, it's not a valid ksh-autoloadable
file (but we're going to autoload it ksh-style anyway).

(2) Run zsh -f and give these commands:

	setopt kshautoload
	autoload +X -k kshtest
	kshtest

(3) Observe the [correct] error:

	zsh: kshtest: function not defined by file

(4) Memory is now corrupted.  At some point soon, usually but not always
during printing of the next prompt, the shell will crash in malloc().