[cmake] Don't require Fortran when looking for arpack

dune-common does no longer require / look for Fortran, so the condition would be always false.

added buildsystem label

added 75 commits

• af040a43...d9b455cb - 74 commits from branch master
• 8c9b46ba - [cmake] Don't require Fortran when looking for arpack

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added 1 commit

• 4cca8c21 - Remove left-over id calls from Hybrid-If

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merged

mentioned in commit 7e9f64ef