debian: install locales-all instead of custom locales generation

The custom way proved to be unreliable - for example does not survive
`locales` package upgrade. So settle on much more reliable way.

Fixes QubesOS/qubes-issues#1195

debian/control

@@ -21,6 +21,7 @@ Depends:
     librsvg2-bin,
     libvchan-xen,
     locales,
+    locales-all,
     ncurses-term,
     net-tools,
     psmisc,

debian/qubes-core-agent.postinst

@@ -115,15 +115,6 @@ case "${1}" in
         done
         dpkg-divert --divert /etc/init/serial.conf.qubes-orig --package qubes-core-agent --rename --add /etc/init/serial.conf
 
-        # make sure locale is really generated
-        current_locale=`grep 'LANG\|LC_ALL' /etc/default/locale|head -n 1|cut -f 2 -d =`
-        if [ -n "$current_locale" ] && ! locale -a | grep -q "$current_locale"; then
-            base=`echo "$current_locale" | cut -f 1 -d .`
-            charmap=`echo "$current_locale.UTF-8" | cut -f 2 -d .`
-            [ -n "$charmap" ] && charmap="-f $charmap"
-            localedef -i $base $charmap $current_locale
-        fi
-
         # Remove old firmware updates link
         if [ -L /lib/firmware/updates ]; then
             rm -f /lib/firmware/updates