[coreboot] superiotool Makefile patch

[Christian Ruppert]

Hey guys,

please apply/commit my patch to the superiotool directory.
Signed-off and brief description can be found in the patch itself.
For further information please take a look at [1] and [2].

[1] http://www.gentoo.org/proj/en/qa/asneeded.xml
[2] http://blog.flameeyes.eu/tag/asneeded/