There is a new pull request by q66 against master on the void-packages repository

https://github.com/void-ppc64/void-packages gimp
https://github.com/void-linux/void-packages/pull/11521

gimp: build with libexecinfo on musl
Gimp unconditionally includes and uses execinfo.h in its app core library, which is used everywhere in gimp. If not installed, gimp will fail to compile. I'm actually not quite sure how it compiled for musl until now, but somehow it did.

See https://github.com/GNOME/gimp/blob/01f940990260146a860f6956ebd962b45b0fc961/app/core/gimpbacktrace-linux.c#L42

A patch file from https://github.com/void-linux/void-packages/pull/11521.patch is attached