* Use gnuconfig package for config file replacement for RISC-V.
This extends the changes in #26035 to handle RISC-V. Before this change,
many packages fail to configure on riscv64 due to config.guess being too
old to know about RISC-V. This is seen out of the box when clingo fails
to build from source due to pkgconfig failing to configure, throwing
error: "configure: error: cannot guess build type; you must specify one".
* Add riscv64 architecture
* Update vendored archspec from upstream project.
These archspec updates include changes needed to support riscv64.
* Update archspec's __init__.py to reflect the commit hash of archspec being used.
Cherry-picked from #25564 so this is standalone.
With this PR we can activate an environment in Spack itself, without computing changes to environment variables only necessary for "shell aware" env activation.
1. Activating an environment:
```python
spack.environment.activate(Environment(xyz)) -> None
```
this basically just sets `_active_environment` and modifies some config scopes.
2. Activating an environment **and** getting environment variable modifications for the shell:
```python
spack.environment.shell.activate(Environment(xyz)) -> EnvironmentModifications
```
This should make it easier/faster to do unit tests and scripting with spack, without the cli interface.
* Isolate bootstrap configuration from user configuration
* Search for build dependencies automatically if bootstrapping from sources
The bootstrapping logic will search for build dependencies
automatically if bootstrapping anything form sources. Any
external spec, if found, is written in a scope that is specific
to bootstrapping.
* Don't clean the bootstrap store with "spack clean -a"
* Copy bootstrap.yaml and config.yaml in the bootstrap area
Reverting from CMake to Make install caused
`-install_path=/usr/local/lib/libzstd.1.dylib` to be hardcoded into the
zstd. Now we explicitly pass the PREFIX into the build command so that
the correct spack install path is saved.
Fixes#26438 and also the ROOT install issue I had :)
