Revert commit 6b58cdd4cf (Ninja: Exclude NVHPC -Werror flags during
Fortran preprocessing, 2023-04-04). Since commit 9d40f01442 (NVHPC: Use
-Werror for COMPILE_OPTIONS_WARNING_AS_ERROR, 2023-04-13), `nvfortran`
can handle the plain `-Werror` flag during preprocessing.
Issue: #24665
The previously-used `-Werror all-warnings` is not supported by
the NVHPC suite of compilers. This previously worked since `-Werror`
was being used and `all-warnings` was being excluded.
We thought this was the correct syntax due to incorrect documentation
about `-Werror`, which stated the argument should be space-separated,
while it should actually be separated with `=` or `,`.
Issue: #24665
The Ninja generator preprocesses Fortran separately in order to scan for
module dependencies. NVHPC's `nvfortran` does not support its `-Werror`
flag while preprocessing with `-E`, so filter it out.
Fixes: #24665
Identify the compilers as `NVHPC` to distinguish it from the older PGI
compilers from which they evolved, and from other `NVIDIA` compilers.
Fixes: #20887
