Compatability module

[ivan-pi]

Another thing which came to mind should be part of an stdlib are: compatibility functions for compilers not fully implementing standards.

Two examples we encountered in CP2K or DBCSR:

• newunit argument for open from F2008. If memory serves it was the Cray compiler which was rather late in implementing this one. Providing higher-level OO wrappers will probably make this a moot point, though.
• findloc from F2008. Implemented in GCC 9.0 & Intel 2018

While missing intrinsics could be provided in a compat module, is redefining an intrinsic probably not doable transparently without using the CPP.

Originally posted by @dev-zero in #1 (comment)

I thought it would be good to break this into a separate issue.

One more example I found are the command_argument_count and get_command_argument intrinsics. Although these are widely supported now, I found the F2KCLI project contains several implementations targeting older compilers.