qemu_cpu.cfg: variants to keep list of intel/AMD CPU models

This way we get per-CPU-model test results entries, instead of a very
long test that checks every CPU model.

This also reuses the "only xxx"/"no xxx" functionality to restrict the
list of CPU models on some tests (e.g. when checking only AMD CPU
models, or when eliminating test for 486 because it doesn't support
CPUID).

This way the test output looks like this:

(1/94) qemu_cpu.check_models.kvm.cpu.intel.486.qemu13: PASS (0.42 s)
(2/94) qemu_cpu.check_models.kvm.cpu.intel.core2duo.qemu13: PASS (0.44 s)
[...]
(25/94) qemu_cpu.cpuid.default.vendor.kvm.cpu.unset.qemu13: PASS (20.58 s)
(26/94) qemu_cpu.cpuid.default.vendor.kvm.cpu.intel.core2duo.qemu13: PASS (20.82 s)
[...]
(47/94) qemu_cpu.cpuid.default.vendor.kvm.cpu.amd.Opteron_G4.qemu13: PASS (20.61 s)
(48/94) qemu_cpu.cpuid.default.vendor.kvm.cpu.amd.Opteron_G5.qemu13: PASS (20.79 s)
(49/94) qemu_cpu.cpuid.default.vendor.nokvm.cpu.intel.core2duo.qemu13: PASS (20.63 s)
(50/94) qemu_cpu.cpuid.default.vendor.nokvm.cpu.intel.kvm32.qemu13: PASS (21.66 s)
[...]
(62/94) qemu_cpu.cpuid.default.vendor.nokvm.cpu.intel.SandyBridge.qemu13: PASS (20.58 s)
(63/94) qemu_cpu.cpuid.default.vendor.nokvm.cpu.intel.Haswell.qemu13: PASS (20.52 s)
(64/94) qemu_cpu.cpuid.default.vendor.nokvm.cpu.amd.qemu64.qemu13: PASS (21.51 s)
(65/94) qemu_cpu.cpuid.default.vendor.nokvm.cpu.amd.phenom.qemu13: PASS (20.53 s)
[...]
(71/94) qemu_cpu.cpuid.default.vendor.nokvm.cpu.amd.Opteron_G5.qemu13: PASS (21.59 s)
(72/94) qemu_cpu.cpuid.custom.vendor.normal.kvm.cpu.unset.qemu13: PASS (20.53 s)
(73/94) qemu_cpu.cpuid.custom.vendor.tooshort.kvm.cpu.unset.qemu13: PASS (0.87 s)
(74/94) qemu_cpu.cpuid.custom.vendor.empty.kvm.cpu.unset.qemu13: PASS (0.81 s)
(75/94) qemu_cpu.cpuid.custom.level.level5.kvm.cpu.unset.qemu13: PASS (20.60 s)
[...]

This allows easier filtering. For example, to restrict testing to tests
specific for the SandyBridge CPU model, one could filter it using:

  $ ./run -t qemu --tests qemu_cpu..SandyBridge

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>