Move the generated `PerfectShuffleTable` from `AArch64PerfectShuffle.h` to one hidden definition in `AArch64PerfectShuffle.cpp`. The three consumers retain direct indexed access. On Darwin arm64 Release, `__TEXT,__const` decreases by 26,240 bytes and stripped AArch64-only `llc` decreases from 48,207,312 to 48,190,816 bytes (-16,496 bytes). Work towards #202616 AI tool disclosure: Co-authored with OpenAI Codex.