Fix up link tests.

Andi Chandler authored Apr 07, 2024 and Administrator committed Apr 07, 2024

(cherry picked from commit 91441d53)

Conform more with Gnome's style.

We use features from vala 0.58 but maintain support for vala version
0.56 as this is a Stable Long-term Support release.

Make it easier to test nibbles on older O/S.

This reverts commit f2da0111.

This reverts commit a65af690.

This reverts commit 9eb28e81.

Make it easier to test nibbles on older O/S.

We use features from vala 0.58 but maintain support for vala version
0.56 as this is a Stable Long-term Support release.

src/gnome-nibbles.vala:146:13-146:18: error: `inline' modifier not applicable on creation methods
  146 |     private inline Nibbles ()
      |             ^~~~~~

Compile against vala fixes for this bug:
vala@ae2cbcd0