[Rpm-maint] [rpm-software-management/rpm] Add armv8* arch variants to rpmrc.in (#425)

[Bernhard Rosenkraenzer]

@mlschroe aarch64 and armv8 are the same CPU, but (obviously, given one is 32bit and one is 64bit) a different ABI -- no need to carry over the legacy float ABI.

For neon, all aarch64 CPUs made so far have it, and it is part of the aarch64 core - however, ARM's docs say "Both floating-point and NEON are required in all standard ARMv8 implementations. However, implementations targeting specialized markets may support the following combinations:
No NEON [...]"

Neither gcc nor clang support aarch64 ABI without NEON for now, so targeting such a CPU is hypothetical anyway.
So far, the only specialized implementations were 32-bit anyway, but we can't rule out a special purpose aarch64 CPU without neon coming out at some point.
Given those (if they ever appear) will be rare and non-standard, if they're worth supporting at all they should probably get a modifier instead of discouraging people targeting aarch64 from using neon.

For crypto, a modifier may well be useful, aarch64 CPUs exist both with and without the crypto extensions.
Do we want to go there even though we don't have something comparable in the x86_64 world where it may make sense to have modifiers for SSE4, AVX, AVX2, SSE4a, SSE4.1, SSE4.2, .....?


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