Add support for excluding maths functions from GPU offload regions

[arporter]

During the NG-Arch NEMO hackathon we concluded that some numerical differences (between the results from NEMO on CPU vs GPU) result from differences in implementation of certain maths functions on those architectures. However, in order to test for correctness of PSyclone transformations, we really want to be able to be confident that any numerical differences are arising from errors. Therefore, it would be good to have support in PSyclone for an option to exclude certain maths functions from being offloaded to the GPU. This would make testing much easier. Note, this is not intended to be something that would be used in production.

[arporter]

Addy found the following paper discussing numerical differences between AMD and NVIDIA GPUs: https://conferences.computer.org/sc-wpub/pdfs/SC-W2024-6oZmigAQfgJ1GhPL0yE3pS/555400a547/555400a547.pdf