Adding NAG Fortran compiler (nagfor) support in the CMake build system.

[ACSimon33]

Description

The changes in this pull request add the necessary compiler flags for the NAG Fortran compiler in the CMake files. The following flags were added in places where they are necessary:

• -recursive (available since nagfor 7.0)
• -i8 (64bit integers)
• -ieee=full (no FPE traps)
• -dcfuns (non-standard double precision complex intrinsic functions: CDABS, DCMPLX, DCONJG, DIMAG, DREAL)
• -thread_safe (enable thread safety)
• -quiet (Suppress compiler banner and summary)

Disabled warnings:

• -w=obs (obsolescent features)
• -w=x77 (F77 extensions)
• -w=ques (questionable usage)
• -w=unused (unused variables, imports, procedures, etc.)

Miscellaneous changes:

The nagfor compiler detected a few lines in the test files that had line lengths of 73. I refactored those to less or equal 72 characters.

Checklist

• The documentation has been updated. (not applicable)
• If the PR solves a specific issue, it is set to be closed on merge. (not applicable)