virtual/linux-sources: rename from virtual/kernel
virtual/linux-sources: rename from virtual/kernel

Upstream Gentoo renamed this virtual, so follow suite.

BUG=None
TEST=`cbuildbot amd64-generic-full` worked
TEST=`cbuildbot arm-tegra2-full` worked
TEST=`cbuildbot x86-generic-full` worked

Change-Id: I2721c85fe83f4ee8a90533eda14813697430e98e
Reviewed-on: https://gerrit.chromium.org/gerrit/18781
Reviewed-by: Olof Johansson <13dc431ca3b0f062f888def8f8ec4662ec608f7d@chromium.org>
Reviewed-by: Sonny Rao <d867fc987a366be56684d1145622524a3ba1efbf@chromium.org>
Commit-Ready: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>

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