host-mtools: Fix build failure introduced by libiconv dependency

Fixes http://autobuild.buildroot.net/results/8ff/8ff7fc94cc3e54f5608f7b4d2e6ccba5fd8e4177/

Also disable parallel make because "make install" is broken, see
http://lists.openembedded.org/pipermail/openembedded-commits/2011-October/134396.html



Signed-off-by: Bernd Kuhls <berndkuhls@hotmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>