qibuild.dylibs: remove dest before trying to create symlink
qibuild.dylibs: remove dest before trying to create symlink

Much safer: this won't fail if we have a broken symlink, for instance.

Change-Id: Ife3e94bb83d0b6957e8cf4ae673921089a632a61
Reviewed-on: http://gerrit.aldebaran.lan:8080/978
Reviewed-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>
Tested-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>

dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,aldebaran/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild