Resolve valgrind failure

Code added by commit id '523207fe'

TEST: qemuxml2argvtest
      ........................................ 40
      ........................................ 80
      ........................................ 120
      ........................................ 160
      ........................................ 200
      ........................................ 240
      .................................        273 OK
==30993== 39 bytes in 1 blocks are definitely lost in loss record 33 of 87
==30993==    at 0x4A0887C: malloc (vg_replace_malloc.c:270)
==30993==    by 0x41E501: fakeSecretGetValue (qemuxml2argvtest.c:33)
==30993==    by 0x427591: qemuBuildDriveURIString (qemu_command.c:2571)
==30993==    by 0x42C502: qemuBuildDriveStr (qemu_command.c:2627)
==30993==    by 0x4335FC: qemuBuildCommandLine (qemu_command.c:6443)
==30993==    by 0x41E8A0: testCompareXMLToArgvHelper (qemuxml2argvtest.c:154
==30993==    by 0x41FE8F: virtTestRun (testutils.c:157)
==30993==    by 0x418BE3: mymain (qemuxml2argvtest.c:506)
==30993==    by 0x4204CA: virtTestMain (testutils.c:719)
==30993==    by 0x38D6821A04: (below main) (in /usr/lib64/libc-2.16.so)
==30993==
==30993== 46 bytes in 1 blocks are definitely lost in loss record 64 of 87
==30993==    at 0x4A0887C: malloc (vg_replace_malloc.c:270)
==30993==    by 0x38D690A167: __vasprintf_chk (in /usr/lib64/libc-2.16.so)
==30993==    by 0x4CB28E7: virVasprintf (stdio2.h:210)
==30993==    by 0x4CB29A3: virAsprintf (virutil.c:2017)
==30993==    by 0x4275B4: qemuBuildDriveURIString (qemu_command.c:2580)
==30993==    by 0x42C502: qemuBuildDriveStr (qemu_command.c:2627)
==30993==    by 0x4335FC: qemuBuildCommandLine (qemu_command.c:6443)
==30993==    by 0x41E8A0: testCompareXMLToArgvHelper (qemuxml2argvtest.c:154
==30993==    by 0x41FE8F: virtTestRun (testutils.c:157)
==30993==    by 0x418BE3: mymain (qemuxml2argvtest.c:506)
==30993==    by 0x4204CA: virtTestMain (testutils.c:719)
==30993==    by 0x38D6821A04: (below main) (in /usr/lib64/libc-2.16.so)
==30993==
==30993== 385 (56 direct, 329 indirect) bytes in 1 blocks are definitely los
==30993==    at 0x4A06B6F: calloc (vg_replace_malloc.c:593)
==30993==    by 0x4C6B2CF: virAllocN (viralloc.c:152)
==30993==    by 0x4C9C7EB: virObjectNew (virobject.c:191)
==30993==    by 0x4D21810: virGetSecret (datatypes.c:642)
==30993==    by 0x41E5D5: fakeSecretLookupByUsage (qemuxml2argvtest.c:51)
==30993==    by 0x4D4BEC5: virSecretLookupByUsage (libvirt.c:15295)
==30993==    by 0x4276A9: qemuBuildDriveURIString (qemu_command.c:2565)
==30993==    by 0x42C502: qemuBuildDriveStr (qemu_command.c:2627)
==30993==    by 0x4335FC: qemuBuildCommandLine (qemu_command.c:6443)
==30993==    by 0x41E8A0: testCompareXMLToArgvHelper (qemuxml2argvtest.c:154
==30993==    by 0x41FE8F: virtTestRun (testutils.c:157)
==30993==    by 0x418BE3: mymain (qemuxml2argvtest.c:506)
==30993==
PASS: qemuxml2argvtest

Interesting side note is that running the test singularly via 'make -C tests
check TESTS=qemuxml2argvtest' didn't trip the valgrind error; however,
running during 'make -C tests valgrind' did cause the error to be seen.

src/qemu/qemu_command.c

@@ -2604,6 +2604,9 @@ cleanup:
     VIR_FREE(tmpscheme);
     VIR_FREE(volimg);
     VIR_FREE(sock);
+    virObjectUnref(sec);
+    VIR_FREE(secret);
+    VIR_FREE(user);
 
     return ret;