update ARM target CPU features

This completes the process. All target CPU features are now
auto-generated by the tools/update_cpu_features.zig script, which
contains all the overrides.

Invoking this tool against LLVM 12rc2 now produces an empty git diff.
ab36a162d0Andrew Kelley committed on 2/28/2021, 4:10:00 AMparent85ab1b0
2 files changedLine totals unavailable