adminDaemonListServers: Don't leak @srv_names array

adminDaemonListServers: Don't leak @srv_names array

When getting a list of servers registered for a daemon, it's
returned as a dynamically allocated array filled in with pointers
to constant strings. Because the array is dynamic, it should be
freed when no longer needed (but not the strings!). Even the
function that creates the array suggests that.

==19446== 48 bytes in 3 blocks are definitely lost in loss record 821 of 1,034
==19446==    at 0x4C2C28E: realloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==19446==    by 0x54BAFC8: virReallocN (viralloc.c:245)
==19446==    by 0x54BB0BE: virExpandN (viralloc.c:294)
==19446==    by 0x54BB391: virInsertElementsN (viralloc.c:436)
==19446==    by 0x164E3D: virNetDaemonGetServerNames (virnetdaemon.c:217)
==19446==    by 0x15616F: adminDaemonListServers (admin_server.c:52)
==19446==    by 0x155B8C: adminDispatchConnectListServers (admin.c:151)
==19446==    by 0x155FD8: adminDispatchConnectListServersHelper (admin_dispatch.h:101)
==19446==    by 0x568E862: virNetServerProgramDispatchCall (virnetserverprogram.c:437)
==19446==    by 0x568E3C3: virNetServerProgramDispatch (virnetserverprogram.c:307)
==19446==    by 0x5687B5B: virNetServerProcessMsg (virnetserver.c:135)
==19446==    by 0x5687C1B: virNetServerHandleJob (virnetserver.c:156)

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>