Package cross-toolchain-x86_64-linux-gnu: Information

- Update components to sync with Sisyphus:
  + binutils 2.46;
  + glibc 2.40.0.224.573a;
  + gcc 15.2.1.
- Update patches from sisyphus_loongarch64.
- Fix glibc FTBFS with GCC 15 by backporting timezone code
  update from upstream.

- Update components to sync with Sisyphus:
  + gcc 14.3.1;
  + glibc 2.40.0.142.2eb180.
- Update patches from sisyphus_loongarch64.

- Unify build for all supported targets.
- Update components to sync with Sisyphus:
  + binutils 2.43;
  + gcc 14.2.1;
  + glibc 2.40.0.69.8566822197.
- Apply patches from sisyphus_loongarch64.
- Move tests from from spec to a checkinstall package.
- Various spec improvements.