Fix common.sh to work in it's new location at /usr/lib/crosutils.
Fix common.sh to work in it's new location at /usr/lib/crosutils.

If we are inside the chroot then we assume that the "gclient" root
is ~/trunk.  If we are outside the chroot we continue with the
previous search mechanism to find the "gclient" root.

Change-Id: Ia40de609ea596228fec2644ff3046e376b112b06

BUG=chromium-os:4230
TEST=run "src/scripts/cros_overlay_list --board tegra2 --variant seaboard" inside and outside the chroot, and under sudo.

Review URL: http://codereview.chromium.org/6265028

Review URL: http://codereview.chromium.org/6344016

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