Patch merged into filo/master: f1f9d46 makefile: don't evaluate empty input

the following patch was just integrated into master:
commit f1f9d467747176421a793ed0302730ee4b6a4bd2
Author: Mathias Krause 
Date:   Mon Mar 5 11:23:24 2012 +0100

makefile: don't evaluate empty input

The output from util/xcompile/xcompile is redirected, so there is
    nothing left for make to $(eval)uate.

Change-Id: I0f482c4b680ca3eded4664c0a57e8525c068feaf
    Signed-off-by: Mathias Krause

Build-Tested: build bot (Jenkins) at Tue Mar  6 16:44:14 2012, giving +1
Reviewed-By: Stefan Reinauer  at Tue Mar  6 21:52:45 2012, giving +2
See http://review.coreboot.org/740 for details.

-gerrit