qemu: Fix memory leak when building -cpu argument
qemu: Fix memory leak when building -cpu argument

Reported by Alex Jia:

==21503== 112 (32 direct, 80 indirect) bytes in 1 blocks are
definitely lost in loss record 37 of 40
==21503==    at 0x4A04A28: calloc (vg_replace_malloc.c:467)
==21503==    by 0x4A8991: virAlloc (memory.c:101)
==21503==    by 0x505A6C: x86DataCopy (cpu_x86.c:247)
==21503==    by 0x507B34: x86Compute (cpu_x86.c:1225)
==21503==    by 0x43103C: qemuBuildCommandLine (qemu_command.c:3561)
==21503==    by 0x41C9F7: testCompareXMLToArgvHelper
(qemuxml2argvtest.c:183)
==21503==    by 0x41E10D: virtTestRun (testutils.c:141)
==21503==    by 0x41B942: mymain (qemuxml2argvtest.c:705)
==21503==    by 0x41D7E7: virtTestMain (testutils.c:696)

jeckersb/libvirt,rlaager/libvirt,novel/fbsd-libvirt,wiedi/libvirt,jfehlig/libvirt,VenkatDatta/libvirt,bjzhang/libvirt,dumbbell/libvirt,jfehlig/libvirt,wiedi/libvirt,libvirt/libvirt,VenkatDatta/libvirt,warewolf/libvirt,andreabolognani/libvirt,dumbbell/libvirt,agx/libvirt,bjzhang/libvirt,rmarwaha/libvirt,fabianfreyer/libvirt,zippy2/libvirt,warewolf/libvirt,elmarco/libvirt,rlaager/libvirt,cbosdo/libvirt,jardasgit/libvirt,cbosdo/libvirt,zhlcindy/libvirt-1.1.4-maintain,jardasgit/libvirt,rmarwaha/libvirt1,taget/libvirt,novel/fbsd-libvirt,datto/libvirt,rmarwaha/libvirt1,andreabolognani/libvirt,emaste/libvirt,olafhering/libvirt,warewolf/libvirt,trainstack/libvirt,taget/libvirt,eskultety/libvirt,shugaoye/libvirt,elmarco/libvirt,nertpinx/libvirt,siboulet/libvirt-openvz,trainstack/libvirt,iam-TJ/libvirt,jfehlig/libvirt,libvirt/libvirt,rlaager/libvirt,foomango/libvirt,foomango/libvirt,emaste/libvirt,agx/libvirt,novel/fbsd-libvirt,agx/libvirt,zhlcindy/libvirt-1.1.4-maintain,crobinso/libvirt,zippy2/libvirt,siboulet/libvirt-openvz,rmarwaha/libvirt,cbosdo/libvirt,libvirt/libvirt,trainstack/libvirt,wiedi/libvirt,novel/fbsd-libvirt,novel/fbsd-libvirt,bjzhang/libvirt,zippy2/libvirt,trainstack/libvirt,cbosdo/libvirt,dumbbell/libvirt,VenkatDatta/libvirt,iam-TJ/libvirt,eskultety/libvirt,crobinso/libvirt,zhlcindy/libvirt-1.1.4-maintain,iam-TJ/libvirt,novel/fbsd-libvirt,olafhering/libvirt,agx/libvirt,datto/libvirt,jeckersb/libvirt,dumbbell/libvirt,warewolf/libvirt,iam-TJ/libvirt,rmarwaha/libvirt1,rmarwaha/libvirt,foomango/libvirt,siboulet/libvirt-openvz,rmarwaha/libvirt,dumbbell/libvirt,jfehlig/libvirt,nertpinx/libvirt,emaste/libvirt,trainstack/libvirt,fabianfreyer/libvirt,foomango/libvirt,shugaoye/libvirt,iam-TJ/libvirt,cbosdo/libvirt,iam-TJ/libvirt,emaste/libvirt,jeckersb/libvirt,crobinso/libvirt,olafhering/libvirt,nertpinx/libvirt,elmarco/libvirt,novel/fbsd-libvirt,jardasgit/libvirt,siboulet/libvirt-openvz,siboulet/libvirt-openvz,eskultety/libvirt,olafhering/libvirt,warewolf/libvirt,emaste/libvirt,datto/libvirt,rmarwaha/libvirt1,taget/libvirt,elmarco/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,shugaoye/libvirt,jardasgit/libvirt,iam-TJ/libvirt,novel/fbsd-libvirt,taget/libvirt,rlaager/libvirt,shugaoye/libvirt,zippy2/libvirt,zhlcindy/libvirt-1.1.4-maintain,jeckersb/libvirt,jeckersb/libvirt,emaste/libvirt,bjzhang/libvirt,andreabolognani/libvirt,bjzhang/libvirt,warewolf/libvirt,crobinso/libvirt,andreabolognani/libvirt,rmarwaha/libvirt,nertpinx/libvirt,rlaager/libvirt,VenkatDatta/libvirt,emaste/libvirt,taget/libvirt,libvirt/libvirt,rmarwaha/libvirt,VenkatDatta/libvirt,rmarwaha/libvirt1,eskultety/libvirt,novel/fbsd-libvirt,andreabolognani/libvirt,elmarco/libvirt,nertpinx/libvirt,foomango/libvirt,fabianfreyer/libvirt,rmarwaha/libvirt1,datto/libvirt,eskultety/libvirt,jeckersb/libvirt,jeckersb/libvirt,wiedi/libvirt,shugaoye/libvirt,wiedi/libvirt,datto/libvirt,trainstack/libvirt,zhlcindy/libvirt-1.1.4-maintain,trainstack/libvirt,agx/libvirt,wiedi/libvirt,wiedi/libvirt,warewolf/libvirt,dumbbell/libvirt