Resolve valgrind error in remoteConfigGetStringList()

Resolve valgrind error in remoteConfigGetStringList()

Commit id 'ed3bac71' introduced the following:

TEST: libvirtdconftest
      ........................................ 40  OK
==25875== 690 (480 direct, 210 indirect) bytes in 30 blocks are definitely lost in loss record 18 of 24
==25875==    at 0x4A06B6F: calloc (vg_replace_malloc.c:593)
==25875==    by 0x4C737DF: virAllocN (viralloc.c:152)
==25875==    by 0x403BC8: remoteConfigGetStringList (libvirtd-config.c:74)
==25875==    by 0x4042CF: daemonConfigLoadOptions (libvirtd-config.c:382)
==25875==    by 0x4052F5: daemonConfigLoadData (libvirtd-config.c:479)
==25875==    by 0x40222C: testCorrupt (libvirtdconftest.c:112)
==25875==    by 0x40321F: virtTestRun (testutils.c:158)
==25875==    by 0x401FEE: mymain (libvirtdconftest.c:228)
==25875==    by 0x40385A: virtTestMain (testutils.c:722)
==25875==    by 0x37C1021A04: (below main) (libc-start.c:225)
==25875==
PASS: libvirtdconftest