NVHPC: Use -Werror for COMPILE_OPTIONS_WARNING_AS_ERROR
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 ,.
Related issues/PRs: #24665 (closed), !8393 (merged)
Edited by Brad King