emacs: add missing chunk in use-qemu.patch for 23.1, create libc.so -> libc.so.6...

emacs: add missing chunk in use-qemu.patch for 23.1, create libc.so -> libc.so.6 link

* prefix-args were built with target compiler but later executed in host
  environment, older emacs versions used prefix-args from qemu, but this
  part was missing in emacs23.1-use-qemu.patch
* Paul Fertser suggested that prefix-args should be built with host
  compiler instead and then without need to use qemu-arm
* When there is no libc.so in ${STAGING_DIR_TARGET}, which is copied to
  treedir, then it tries to use libc.so from host, which is wrong.
  Added something like angstrom-libc-fixup-hack.bb but for treedir.
* Also add dbus to DEPENDS to make sure configure finds it for bindings.

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>