qi_install_program: Look in src dir, not build dir.

Since the doc tells us not to use this for generated stuff,
it does not make sense to look in build dir.

Change-Id: I6325aac8db5cf13a58126736de76d93d50ba62d6
Reviewed-on: http://gerrit.aldebaran.lan:8080/10752
Reviewed-by: dmerejkowsky <dmerejkowsky@aldebaran-robotics.com>
Tested-by: mnottale <mnottale@aldebaran-robotics.com>