rpc: Plug memory leaks on doRemoteOpen() failure path

rpc: Plug memory leaks on doRemoteOpen() failure path

Detected by valgrind. Leaks are introduced in commit c1b2264.

* src/remote/remote_driver.c (doRemoteOpen): free client program memory in failure path.

* How to reproduce?
% valgrind -v --leak-check=full virsh -c qemu:

* Actual result

==3969== 40 bytes in 1 blocks are definitely lost in loss record 8 of 28
==3969==    at 0x4A04A28: calloc (vg_replace_malloc.c:467)
    ==3969==    by 0x4C89C41: virAlloc (memory.c:101)
    ==3969==    by 0x4D5A236: virNetClientProgramNew (virnetclientprogram.c:60)
    ==3969==    by 0x4D47AB4: doRemoteOpen (remote_driver.c:658)
    ==3969==    by 0x4D49FFF: remoteOpen (remote_driver.c:871)
    ==3969==    by 0x4D13373: do_open (libvirt.c:1196)
    ==3969==    by 0x4D14535: virConnectOpenAuth (libvirt.c:1422)
    ==3969==    by 0x425627: main (virsh.c:18537)
    ==3969==
    ==3969== 40 bytes in 1 blocks are definitely lost in loss record 9 of 28
    ==3969==    at 0x4A04A28: calloc (vg_replace_malloc.c:467)
    ==3969==    by 0x4C89C41: virAlloc (memory.c:101)
    ==3969==    by 0x4D5A236: virNetClientProgramNew (virnetclientprogram.c:60)
    ==3969==    by 0x4D47AD7: doRemoteOpen (remote_driver.c:664)
    ==3969==    by 0x4D49FFF: remoteOpen (remote_driver.c:871)
    ==3969==    by 0x4D13373: do_open (libvirt.c:1196)
    ==3969==    by 0x4D14535: virConnectOpenAuth (libvirt.c:1422)
    ==3969==    by 0x425627: main (virsh.c:18537)
    ==3969==
    ==3969== LEAK SUMMARY:
    ==3969==    definitely lost: 80 bytes in 2 blocks

Signed-off-by: Alex Jia <ajia@redhat.com>