exec_ping: Permit loading libraries from /usr for libidn2 (and do a release)

The iputils-ping package now depends on libidn2-0 which is shipped
as /usr/lib/*/libidn2.so.0, so we now need to let the test load
libraries from /usr/lib and not just from /lib.

Running VERBOSE=1 /usr/lib/apparmor-demo/exec_ping.sh yielded:

[...]                                                                                                               
runtestfg: ---- Output of /usr/lib/apparmor-demo/exec_ping ----                                                     
runtestfg:   /bin/ping: error while loading shared libraries: libidn2.so.0: cannot open shared object file: No such file or directory
runtestfg:   /usr/lib/apparmor-demo/exec_ping: parent: waiting for child 6064                                       
runtestfg:   /usr/lib/apparmor-demo/exec_ping: parent: child wait status 32512                                      
runtestfg:   /usr/lib/apparmor-demo/exec_ping: parent: child exited 127                                             
runtestfg:   FAIL, child exited with status 127                                                                     
[...]

• 998911f4 exec_ping: Permit loading libraries from /usr for libidn2
• 1e3b0b49 Release apparmor-demo version 0.4+20150326.2