imlib configure stuff

[Tom Tromey <tromey creche cygnus com>]

Hopefully this is an ok place to post imlib weirdnesses.  I found a
couple:

1. Why not have a top-level configure.in that runs configure in each
subdir?  Likewise, a top-level Makefile?  It would be trivial to set
up, and more convenient than what is there now.

2. Each configure runs `clear'.  This is bogus.  Each configure script
also prints a bunch of information that I don't need (e.g.,
"Configuring Imlib" -- I already know this).  There is no way to turn
this off.  At the very least, these echoes should respect --silent.
There is an autoconf macro that does this automatically.

Tom