Draft: nvhpc compiler support on grace CPU

Start adding support for nvhpc compiler with SWIFT on grace ARM CPU.

Mostly a guess but it compiles using the nvc compiler on COSMA using configure:

./configure --disable-mpi --disable-hand-vec --enable-compiler-warnings=yes

and a set of packages built with the system GCC compiler.

Still some compiler warnings to worry about, so need to poison compiler warnings, but adding dummy size to the empty structs stops the compiler from crashing.