qemuBuildNumaArgStr: Simplify @nodeBackends
qemuBuildNumaArgStr: Simplify @nodeBackends

Instead of array of pointers to individual buffers it can be
array of buffers directly. This also fixes the following memleak:

==22516== 96 bytes in 4 blocks are definitely lost in loss record 166 of 195
==22516==    at 0x4C2EF26: calloc (vg_replace_malloc.c:711)
==22516==    by 0x5D2C7D5: virAlloc (viralloc.c:144)
==22516==    by 0x56FAABD: qemuBuildNumaArgStr (qemu_command.c:7543)
==22516==    by 0x5701835: qemuBuildCommandLine (qemu_command.c:10112)
==22516==    by 0x575D794: qemuProcessCreatePretendCmd (qemu_process.c:6568)
==22516==    by 0x113338: testCompareXMLToArgv (qemuxml2argvtest.c:549)
==22516==    by 0x138CA3: virTestRun (testutils.c:180)
==22516==    by 0x136CD1: mymain (qemuxml2argvtest.c:2825)
==22516==    by 0x13AD58: virTestMain (testutils.c:1118)
==22516==    by 0x137351: main (qemuxml2argvtest.c:2874)

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

crobinso/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,andreabolognani/libvirt,jfehlig/libvirt,nertpinx/libvirt,jfehlig/libvirt,eskultety/libvirt,jardasgit/libvirt,libvirt/libvirt,andreabolognani/libvirt,olafhering/libvirt,libvirt/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,nertpinx/libvirt,libvirt/libvirt,jardasgit/libvirt,andreabolognani/libvirt,eskultety/libvirt,crobinso/libvirt,eskultety/libvirt,olafhering/libvirt,zippy2/libvirt,jfehlig/libvirt,zippy2/libvirt,olafhering/libvirt,eskultety/libvirt,eskultety/libvirt,fabianfreyer/libvirt,olafhering/libvirt,zippy2/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,nertpinx/libvirt,jfehlig/libvirt,nertpinx/libvirt,nertpinx/libvirt,zippy2/libvirt,crobinso/libvirt,crobinso/libvirt,libvirt/libvirt