Log Message:
rust-bin: fix checksum for NetBSD/aarch64, and new bits for NetBSD/powerpc.

I admit that I cannot fully explain how the NetBSD/aarch64 checksum
managed to mismatch, but at least the bits on ftp.netbsd.org and
cdn.netbsd.org agree, also with the local build results I had for
the cross-compiled bits.

Deal with NetBSD/powerpc: 1.74.0 revealed that the bootstrap
kit from rust 1.73.0 (also used here) mis-compiles, ref.
  https://github.com/rust-lang/rust/issues/118099
The new powerpc bootstrap kit is therefore natively compiled, with
an external LLVM (therefore has an exteranl dependency on LLVM)
instead of the rust-supplied internal one / cross-compiled.  Also,
remove vestiges of hints of being able to use this package on
NetBSD/powerpc 8.x, ref. note to tech-pkg of November 28; newer
rust's embedded LLVM uses newer C++ features than what netbsd-8
supports "out of the box".

Bump PKGREVISION, even though this only fixes buildability for
NetBSD/aarch64 and changes contents for NetBSD/powerpc.