Add support for registration of multiple versions of CPU models.
The existing CPU models will be registered with a "-v1" suffix.
The -noTSX, -IBRS, and -IBPB CPU model variants will become
versions of the original models in a separate patch, so
make sure we register no versions for them.
Backports commit dcafd1ef0af227ef87f7a6dec8fc66d7d2e2442d from qemu
We've currently got 18 architectures in QEMU, and thus 18 target-xxx
folders in the root folder of the QEMU source tree. More architectures
(e.g. RISC-V, AVR) are likely to be included soon, too, so the main
folder of the QEMU sources slowly gets quite overcrowded with the
target-xxx folders.
To disburden the main folder a little bit, let's move the target-xxx
folders into a dedicated target/ folder, so that target-xxx/ simply
becomes target/xxx/ instead.
Backports commit fcf5ef2ab52c621a4617ebbef36bf43b4003f4c0 from qemu
