Backward compatibility for ARM64.

[aquynh]

Feature

• New architecture module
• Support for processor extension
• Add more instruction details (elaborated below)
• Binding support for: language
• Other (elaborated below)

Please have API backward compatibility, so consts like CS_ARCH_ARM64, CS_ARM64_xxx still work out of the box - without having to do any configuration

[Rot127]

For Python they are still missing (related to #2468).

But for C we have the compatibility header. Which can be enabled with a single "#define" (as documented here).

Switching to v6-Alpha or any other version requires code changes anyways. Because instruction enumerations and details got more precise. Just as in the releases from v3, v4 and v5. With v6 this should no longer happen from now on.
So if people have to touch their code a last time between releases anyways, in my opinion a single #define is not too much.