enter_chroot.sh: always generate en_US locales

The buildbot code forces the en_US.UTF8 locale itself, and does so inside
of the chroot, so our auto-detection code doesn't catch it.  Always create
these locales that the buildbot uses.

BUG=None
TEST=cleared out locales, emptied out active locale env vars, ran enter_chroot, saw that en_US{,UTF8} were created

Change-Id: I9ad65007a340333e19743985c9cbeea9403823fa
Reviewed-on: http://gerrit.chromium.org/gerrit/6168
Reviewed-by: David James <davidjames@chromium.org>
Tested-by: David James <davidjames@chromium.org>
diff --git a/sdk_lib/enter_chroot.sh b/sdk_lib/enter_chroot.sh
index 2fd0d6a..33fb303 100755
--- a/sdk_lib/enter_chroot.sh
+++ b/sdk_lib/enter_chroot.sh
@@ -316,7 +316,9 @@
 
     # Make sure user's requested locales are available
     # http://crosbug.com/19139
-    locales=$(printf '%s\n' ${LANG} \
+    # And make sure en_US{,.UTF-8} are always available as
+    # that what buildbot forces internally
+    locales=$(printf '%s\n' en_US en_US.UTF-8 ${LANG} \
       $LC_{ADDRESS,ALL,COLLATE,CTYPE,IDENTIFICATION,MEASUREMENT,MESSAGES} \
       $LC_{MONETARY,NAME,NUMERIC,PAPER,TELEPHONE,TIME} | \
       sort -u | sed '/^C$/d')