* Use `global_asm!` instead of external assembly files
This commit moves the external assembly files of the `wasmtime-fiber`
crate into `global_asm!` blocks defined in Rust. The motivation for
doing this is not very strong at this time, but the points in favor of
this are:
* One less tool needed to cross-compile Wasmtime. A linker is still
needed but perhaps one day that will improve as well.
* A "modern" assembler, built-in to LLVM, is used instead of whatever
appears on the system.
The first point hasn't really cropped up that much and typically getting
an assembler is just as hard as getting a linker nowadays. The second
point though has us using `hint #xx` in aarch64 assembly instead of the
actual instructions for assembler compatibility, and I believe that's no
longer necessary because the LLVM assembler supports the modern
instruction names.
The translation of the x86/x86_64 assembly has been done to Intel
syntax as well as opposed to the old AT&T syntax since that's Rust's
default. Additionally s390x still remains in an external assembler file
because `global_asm!` is still unstable in Rust on that platform.
* Simplify alignment specification
* Temporarily disable fail-fast
* Add `.cfi_def_cfa_offset 0` to fix CI
* Turn off fail-fast
* Review comments
4543a07bb5