NOTES:

- Add /etc/fpm/config-file.toml
  - Use to minimize the patching needed for packages
  - Add per-compiler information here:

New fpm has per-compiler features:

# Release feature with base optimization, then per-compiler extensions
release.flags = "-O3"  # Base optimization for ALL compilers (applied first)
release.gfortran.flags = "-mtune=generic -funroll-loops"
release.ifort.flags = "-unroll"     # Unix/Linux/macOS Intel
release.ifx.flags = "-unroll"       # Intel oneAPI

Adapt info on dpkg-buildflags to this format.
Need to enable new compilers:
eg
debug.flang_21.flags=""

Adapt is_compiler_key() in fpm to do this.
Add :
release.additional_compilers = [ 'flang-21', ]
etc
