Update gimp to 2.8.22. (1)

• Move libsoup to the helpbrowser dependancy (2)
• Gimp plugins need kern.ipc.shm_allow_removed=1, which is default for 11.0-R and newer. Add pkg-message for 10.x (3)
• Move desktop-file-utils so it only applies to the gimp-app port.

PR: 219156 (based on)(1), 214751 (2), 204919 (3), 206097 (3)
Submitted by: mi@ (1), Christian Heckendorf <heckendorfc@gmail.com> (2)