Changes to support ARM cross compilation.
Changes to support ARM cross compilation.

Added a flag to allow verbose make-kpkg and a flag to specify the
cross compile tools.

Changed the default output_root to use ARCH in the path.

Modified determination of ARCH and changed ARCH=arm to the more correct
ARCH=armel. Also set KPKG_ARCH=arm for compliance with kernel makefile.

Disabled the setarch command when it fails and instead alias uname to
echo ARCH.

A call to compile for arm will look like:
./build_kernel.sh --config=path/to/config --cross_compile=arm-linux-gnueabi- \
[--verbose]

Review URL: http://codereview.chromium.org/501019

BugRoger/scripts,coreos/scripts,marineam/coreos-scripts,marineam/coreos-scripts,vmware/coreos-scripts,bcwaldon/coreos-scripts,andrejro/coreos--scripts,endocode/scripts,andrejro/coreos--scripts,zhang0137/scripts,zhang0137/scripts,smilart/scripts,marineam/coreos-scripts,vmware/coreos-scripts,endocode/scripts,trnubo/scripts,crawford/scripts,sigma/coreos-scripts,mischief/scripts,nicescale/scripts,zhang0137/scripts,fivethreeo/scripts,crawford/scripts,vmware/coreos-scripts,bcwaldon/coreos-scripts,BugRoger/scripts,mjg59/scripts,gtank/scripts,glevand/coreos--scripts,andrejro/coreos--scripts,mjg59/scripts,sigma/coreos-scripts,smilart/scripts,mischief/scripts,gtank/scripts,fivethreeo/scripts,sigma/coreos-scripts,endocode/scripts,gtank/scripts,mischief/scripts,nicescale/scripts,fivethreeo/scripts,smilart/scripts,trnubo/scripts,mjg59/scripts,coreos/scripts,BugRoger/scripts,bcwaldon/coreos-scripts,trnubo/scripts,nicescale/scripts,crawford/scripts,glevand/coreos--scripts