Run postinst during rootfs generation

== Background ==
In poky we have 2 types of postinst scripts: one (type-1) can be (and has already been) run at rootfs generation time and the other (type-2) has to be delayed to the first-boot of target device. Type-2 makes target device's first-boot slow and it would be great if we can fix it and convert it to type-1.
== Tasks ==
* We can instrument a first-boot with minimal/sato first to see which postinstalls take the most time and then prioritize those ones to fix.
* Dexuan has figured out a list of 33 recipes in total(recipes with the same name but with different versions are counted once) we possibly need to fix. For the recipes, we need try to find recipe-specific ways(use appropriately modified native utilities to generate caches, files, etc as necessary on the target filesystem).
** Saul: can we break this down to what's sato and minimal?
** RP: how long were these different groups of postinstall taking on the target device?
* Wolfgang Hauser
 Beside the discussed changes, the postinst scripts should be executed in the dependency order.
 At the time, the scripts are executed in alphabetic order, which breaks the image generation if depended packages are not
 in alphabetic order, e.g. busybox and busybox subpackages (busybox-mdev).
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11 recipes: these could be easily fixed since Scott Garman has added the properly-adjusted utilities "adduser, addgroup, pwconv, etc". The owners of the recipes can help to fix them.
 meta/recipes-devtools/distcc/distcc_2.18.3.bb
 meta/recipes-extended/cronie/cronie_1.4.7.bb
 meta/recipes-extended/at/at_3.1.12.bb:47
 meta/recipes-support/hal/hal.inc:45
 meta/recipes-core/dbus/dbus.inc:49
 meta/recipes-connectivity/openssh/openssh_5.8p2.bb
 meta/recipes-connectivity/ppp-dialin/ppp-dialin_0.1.bb
 meta/recipes-graphics/x11-common/xserver-nodm-init.bb
 meta/recipes-multimedia/pulseaudio/pulseaudio.inc:87
 meta/recipes-extended/shadow/shadow_4.1.4.3.bb:125
 meta/classes/libc-package.bbclass
6 recipes: these should be easily fixed since the scripts are not related to special native utilites.
 mete/recipes-extended/sudo/sudo.inc
 mete/recipes-extended/sysklogd/sysklogd.inc
 meta/classes/update-rc.d.bbclass
 mete/recipes-connectivity/ppp/ppp_2.4.5.bb
 mete/recipes-graphics/pango/pango.inc
 mete/recipes-gnome/gtk+/gtk+.inc
 
4 recipes: we may need to add gtk-update-icon-cache-native.
 meta/classes/gtk-icon-cache.bbclass
 mete/recipes-gnome/librsvg/librsvg_2.32.1.bb
 mete/recipes-gnome/gdk-pixbuf/gdk-pixbuf_2.22.1.bb
 mete/recipes-sato/sato-icon-theme/sato-icon-theme.inc
3 recipes: need to add gconftool-2-native?
 meta/classes/gconf.bbclass
 mete/recipes-graphics/mutter/mutter.inc
 mete/recipes-sato/matchbox-sato/matchbox-session-sato_0.1.bb
3 recipes: "dpkg --configure, opkg-cl configure": looks it's possible to fix them if we specify proper paramaters?
 mete/recipes-devtools/dpkg/dpkg.inc
 mete/recipes-devtools/opkg/opkg_svn.bb
 mete/recipes-devtools/opkg/opkg_0.1.8.bb
1 recipe: prelink: Mark Hatle alreay fixed this: http://git.pokylinux.org/cgit/cgit.cgi/poky/commit/?id=d18aba9c1cb5b2cf77cfb2dff150e9003b2e63ef.
 mete/recipes-devtools/prelink/prelink_git.bb
1 recipe: "/etc/init.d/populate-volatile.sh update ; DBUSPID=`pidof dbus-daemon`": We can't fix this one.
 mete/recipes-connectivity/wpa-supplicant/wpa-supplicant-0.7.inc
The below 4 recipes need the related utilities and need more investigation. 
1 recipe: update-modules
 mete/recipes-kernel/update-modules/update-modules_1.0.bb
1 recipe: systemctl
 mete/recipes-connectivity/avahi/avahi.inc
1 recipe: fc-cache
 mete/recipes-graphics/ttf-fonts/liberation-fonts_1.04.bb:37
1 recipe: gtk-query-immodules-2.0
 mete/recipes-sato/matchbox-keyboard/matchbox-keyboard_git.bb