When GIMP 2.8 is built with any prefix other than /usr or /usr/local, a lot
of plug-ins won't work.
I asked about this in the GIMP IRC channel today, and user mikachu helped me
fix it with a simple edit.
add the following to the "Libs:" line in the file gimp-2.0.pc.
-Wl,-rpath,${libdir}
In other words, change
Libs: -L${libdir} -lgimp-@GIMP_API_VERSION@ -lgimpmath-@GIMP_API_VERSION@
-lgimpconfig-@GIMP_API_VERSION@ -lgimpcolor-@GIMP_API_VERSION@
-lgimpbase-@GIMP_API_VERSION@ @RT_LIBS@
to
Libs: -Wl,-rpath,${libdir} -L${libdir} -lgimp-@GIMP_API_VERSION@
-lgimpmath-@GIMP_API_VERSION@ -lgimpconfig-@GIMP_API_VERSION@
-lgimpcolor-@GIMP_API_VERSION@ -lgimpbase-@GIMP_API_VERSION@ @RT_LIBS@
You can make this change before or after you build GIMP.
To change it before you build, the file is gimp-2.0.pc and it's located in
the root of the source directory.
To change it after you've already built it, the file is
lib/pkgconfig/gimp-2.0.pc
