Add a wrapper script called 'configure' at the top level, which runs

the real configure script from the unix subdirectory, but with cwd
unchanged so that you end up doing a VPATH build in the top-level
source directory.

Should, ideally, placate the people who expect 'configure' to be at
the top level, while still letting _me_ keep all the Unix-specific
stuff in the Unix subdirectory.

[originally from svn r9241]

configure

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+$(echo "$0" | sed '$s!configure$!unix/configure!') "$@"