Update a few GNUstep ports:

[nc]

Summary

Update a few GNUstep ports:

• devel/gnustep-make: Update to 2.8.0
• lang/gnustep-base: Update to 1.27.0
• x11-toolkits/gnustep-back: update to 0.28.0
• x11-toolkits/gnustep-gui: update to 0.28.0

Also bump PORTREVISION on dependent ports

Test Plan

Passes poudriere

[nc]

Accidfentally bumped PORTVERSION instead of PORTREVISION for ftp/gnustep-ftp, so bump the right thing.