Plug some mem leaks in gdbus-peer test

Plug some mem leaks in gdbus-peer test

==29535== 56 (24 direct, 32 indirect) bytes in 1 blocks are definitely lost in loss record 1,112 of 1,264
==29535==    at 0x4005BDC: malloc (vg_replace_malloc.c:195)
==29535==    by 0x4057094: g_malloc (gmem.c:134)
==29535==    by 0x406F2D6: g_slice_alloc (gslice.c:836)
==29535==    by 0x406F364: g_slice_copy (gslice.c:858)
==29535==    by 0x403A9B2: g_error_copy (gerror.c:160)
==29535==    by 0x42066D3: initable_init (gdbusconnection.c:2314)
==29535==    by 0x41A73E5: g_initable_init (ginitable.c:105)
==29535==    by 0x41A7587: g_initable_new_valist (ginitable.c:218)
==29535==    by 0x41A742A: g_initable_new (ginitable.c:138)
==29535==    by 0x4206DCC: g_dbus_connection_new_for_address_sync (gdbusconnection.c:2585)
==29535==    by 0x804D63A: test_nonce_tcp (gdbus-peer.c:1229)

==29535== 107 (24 direct, 83 indirect) bytes in 1 blocks are definitely lost in loss record 1,188 of 1,264
==29535==    at 0x4005BDC: malloc (vg_replace_malloc.c:195)
==29535==    by 0x4057094: g_malloc (gmem.c:134)
==29535==    by 0x406F2D6: g_slice_alloc (gslice.c:836)
==29535==    by 0x406F364: g_slice_copy (gslice.c:858)
==29535==    by 0x403A9B2: g_error_copy (gerror.c:160)
==29535==    by 0x42066D3: initable_init (gdbusconnection.c:2314)
==29535==    by 0x41A73E5: g_initable_init (ginitable.c:105)
==29535==    by 0x41A7587: g_initable_new_valist (ginitable.c:218)
==29535==    by 0x41A742A: g_initable_new (ginitable.c:138)
==29535==    by 0x4206DCC: g_dbus_connection_new_for_address_sync (gdbusconnection.c:2585)
==29535==    by 0x804D8E8: test_nonce_tcp (gdbus-peer.c:1259)

==29535== 112 (24 direct, 88 indirect) bytes in 1 blocks are definitely lost in loss record 1,193 of 1,264
==29535==    at 0x4005BDC: malloc (vg_replace_malloc.c:195)
==29535==    by 0x4057094: g_malloc (gmem.c:134)
==29535==    by 0x406F2D6: g_slice_alloc (gslice.c:836)
==29535==    by 0x406F364: g_slice_copy (gslice.c:858)
==29535==    by 0x403A9B2: g_error_copy (gerror.c:160)
==29535==    by 0x42066D3: initable_init (gdbusconnection.c:2314)
==29535==    by 0x41A73E5: g_initable_init (ginitable.c:105)
==29535==    by 0x41A7587: g_initable_new_valist (ginitable.c:218)
==29535==    by 0x41A742A: g_initable_new (ginitable.c:138)
==29535==    by 0x4206DCC: g_dbus_connection_new_for_address_sync (gdbusconnection.c:2585)
==29535==    by 0x804D79A: test_nonce_tcp (gdbus-peer.c:1248)

==29535== 73 (24 direct, 49 indirect) bytes in 1 blocks are definitely lost in loss record 1,152 of 1,264
==29535==    at 0x4005BDC: malloc (vg_replace_malloc.c:195)
==29535==    by 0x4057094: g_malloc (gmem.c:134)
==29535==    by 0x406F2D6: g_slice_alloc (gslice.c:836)
==29535==    by 0x406F364: g_slice_copy (gslice.c:858)
==29535==    by 0x403A9B2: g_error_copy (gerror.c:160)
==29535==    by 0x42066D3: initable_init (gdbusconnection.c:2314)
==29535==    by 0x41A73E5: g_initable_init (ginitable.c:105)
==29535==    by 0x41A7587: g_initable_new_valist (ginitable.c:218)
==29535==    by 0x41A742A: g_initable_new (ginitable.c:138)
==29535==    by 0x4206DCC: g_dbus_connection_new_for_address_sync (gdbusconnection.c:2585)
==29535==    by 0x804C6CE: test_peer (gdbus-peer.c:803)

Bug #628331.