The majority of these are in comments, some in doc comments which might
affect the generated documentation, and a few in parameter names -
nothing that should be breaking, however.
Notable changes:
`_i386`, `_i486`, and `_i686` are renamed to `i386`, `i486`,
and `i686` respectively. `std.zig.fmtId` is enhanced to support
formatting `i386` as `@"i386"`.
Some CPU features which are actually CPU models have been
properly flattened, such as `apple_a12`, `apple_a13`, `apple_a7`,
`cortex_a78c`, `exynos_m4`, `neoverse_e1`, `neoverse_n1`,
`neoverse_n2`, `neoverse_v1`.
Some CPU features have been added and some have been removed, following
LLVM's lead.
CSky CPU features support is added.