Auto merge of #100260 - ehuss:compiletest-target-cfg, r=Mark-Simulacrum

compiletest: use target cfg instead of hard-coded tables

This changes compiletest to use `rustc --print=cfg` to dynamically determine the properties of a target when matching `ignore` and `only` rules instead of using hard-coded tables or target-triple parsing (which don't always follow the `<arch><sub>-<vendor>-<sys>-<abi>` pattern). The benefit here is that it will more accurately match the target properties, and not require maintaining these extra tables.

This also adds matching the `target_family` in ignore rules. The primary benefit here is so that `ignore-wasm` works as expected (matching all wasm-like targets). There were already several tests that had `ignore-wasm` in them (which previously had no effect), so it is evident that some people expected that to work. This also adds `ignore-unix/only-unix`.

There is some risk that this changes the behavior from before since the tables aren't quite the same as the target properties. However, I did fairly extensive comparisons to see what would be different. https://gist.github.com/ehuss/5bf7ab347605160cefb6f84ba5ea5f6b contains a full list of differences for all targets for all tests. I do not think any of the affected target/test combinations are things that are actually tested in CI. I tested several of the more unusual test images (test-various, dist-various-1, wasm32), and they seem fine.

A summary of most of the reasons behind the differences:

- wasm64-unknown-unknown wasm32-wasi now match "wasm"
- Targets now match "gnu" because they have target_env=gnu
    - aarch64-wrs-vxworks
    - armv7-wrs-vxworks-eabihf
    - i686-wrs-vxworks
    - powerpc-wrs-vxworks
    - powerpc64-wrs-vxworks
    - x86_64-wrs-vxworks
- wasm64-unknown-unknown now matches wasm64
- x86_64-unknown-none-linuxkernel no longer matches "linux", but will match "gnu" and "none"
- Various arm targets now match "aarch64" or "arm":
    - arm64_32-apple-watchos
    - armebv7r-none-eabi
    - armv6-unknown-freebsd
    - armv6-unknown-netbsd-eabihf
    - armv6k-nintendo-3ds
    - armv7-wrs-vxworks-eabihf
    - armv7a-kmc-solid_asp3-eabi
    - armv7a-kmc-solid_asp3-eabihf
    - armv7a-none-eabi
    - armv7a-none-eabihf
    - armv7k-apple-watchos
    - armv7r-none-eabi
    - armv7r-none-eabihf
- Now matches "thumb" and "arm"
    - thumbv4t-none-eabi
    - thumbv6m-none-eabi
    - thumbv7a-pc-windows-msvc
    - thumbv7a-uwp-windows-msvc
    - thumbv7em-none-eabi
    - thumbv7em-none-eabihf
    - thumbv7m-none-eabi
    - thumbv7neon-linux-androideabi
    - thumbv7neon-unknown-linux-gnueabihf
    - thumbv7neon-unknown-linux-musleabihf
    - thumbv8m.base-none-eabi
    - thumbv8m.main-none-eabi
- asmjs-unknown-emscripten now matches "wasm32" because that it is its defined arch
- avr-unknown-gnu-atmega328 now matches "none" (because target_os="none")
- now matches 64bit:
    - bpfeb-unknown-none
    - bpfel-unknown-none
    - sparcv9-sun-solaris
- now matches endian-big:
    - m68k-unknown-linux-gnu
- now matches 16bit:
    - msp430-none-elf
- now matches 32bit:
    - arm64_32-apple-watchos
- now matches riscv32 (and needs-asm-support):
    - riscv32gc-unknown-linux-gnu
    - riscv32gc-unknown-linux-musl
    - riscv32i-unknown-none-elf
    - riscv32im-unknown-none-elf
    - riscv32imac-unknown-none-elf
    - riscv32imac-unknown-xous-elf
    - riscv32imc-esp-espidf
    - riscv32imc-unknown-none-elf
    - riscv64imac-unknown-none-elf

Author: bors