Fixed a leak found by ASan:
Direct leak of 160 byte(s) in 2 object(s) allocated from:
#0 0x7f511fe11518 in calloc (/lib/x86_64-linux-gnu/libasan.so.5+0xe9518)
#1 0x7f511fc76373 in zalloc ../../git/wayland/src/wayland-private.h:232
#2 0x7f511fc76373 in proxy_create ../../git/wayland/src/wayland-client.c:422
#3 0x7f511fc79dcc in create_outgoing_proxy ../../git/wayland/src/wayland-client.c:651
#4 0x7f511fc79dcc in wl_proxy_marshal_array_constructor_versioned ../../git/wayland/src/wayland-client.c:736
#5 0x7f511fc7b17b in wl_proxy_marshal_constructor_versioned ../../git/wayland/src/wayland-client.c:873
#6 0x5583e5348f43 in wl_registry_bind /home/pq/local/include/wayland-client-protocol.h:1165
#7 0x5583e535140b in bind_to_singleton_global ../../git/weston/tests/weston-test-client-helper.c:1863
#8 0x5583e5348752 in alpha_blend_monotonic ../../git/weston/tests/alpha-blending-test.c:219
#9 0x5583e5348571 in wrapalpha_blend_monotonic ../../git/weston/tests/alpha-blending-test.c:200
#10 0x5583e53554cc in run_test ../../git/weston/tests/weston-test-runner.c:162
#11 0x5583e5355b6d in run_case ../../git/weston/tests/weston-test-runner.c:277
#12 0x5583e5355913 in for_each_test_case ../../git/weston/tests/weston-test-runner.c:235
#13 0x5583e5355df5 in testsuite_run ../../git/weston/tests/weston-test-runner.c:311
#14 0x7f511aaaf752 in client_thread_routine ../../git/weston/tests/weston-test.c:404
#15 0x7f511f88cfa2 in start_thread /build/glibc-vjB4T1/glibc-2.28/nptl/pthread_create.c:486
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>