enter_chroot: auto generate user locales
enter_chroot: auto generate user locales

Since we no longer force LC_ALL=C on everyone, the few times that perl
does get run by people, it spews the expected "Setting locale failed"
warnings.  This isn't as big a deal as with Debian systems as perl usage
is uncommon in Gentoo.

This is also highlights the long-existing small issue of only specific
locales being available in the chroot.  So for non US english speaking
users, they've been having non-optimal experiences.

So parse the user's active locale and automatically generate the missing
ones in the chroot so that when they do enter, things "just work".

BUG=chromium-os:19139
TEST=set locale to non-existent ones, enter_chroot, & verify locales are created

Change-Id: I43f809a1ee1472e4797edab0f32cecf582ea8b48
Reviewed-on: http://gerrit.chromium.org/gerrit/5986
Reviewed-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>

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