An `eye` function that accepts the default integer and another integer kind simultaneously

[certik]

@zaikunzhang

Thank you @kargl for the explanation. Is there a way to do this data mining automatically, or does the user have to do it manually?

This has been discussed previously here:

• Portable way to check existence of ISO_FORTRAN_ENV intrinsic module - #9 by milancurcic
• Which Kinds are Real?
• Discussion on Fortran's type-kind distinction
• Best way to declare a double precision in Fortran?