Create a RULE to detect DUNE license as gcc-linking-exception-2.0

[DennisClark]

Please use the text at https://dune-project.org/about/license/ to create a RULE that points to gcc-linking-exception-2.0 (often referred to as the runtime exception).

https://scancode-licensedb.aboutcode.org/gcc-linking-exception-2.0.html

The text on the DUNE page is basically a specific adaptation of that license exception.

[AyanSinhaMahapatra]

@DennisClark but we have this added as https://scancode-licensedb.aboutcode.org/dune-exception.html are you asking to remove and requialify this license as a gcc-linking-exception-2.0 rule?

[DennisClark]

@AyanSinhaMahapatra actually the new dune-exception is fine, thanks, please keep it.