Commit 1e6acbd4e1 modified the
generated enum recipes to run gimp-mkenums from the source
directory, instead of the build directory, so that only the
basenames of the corresponding header files would appear in
the comment at the top of the generated files. This was a
mistake -- $(GIMP_MKENUMS) is expecting to be invoked from the
build directory.
Switch back to running gimp-mkenums from the build directory. To
avoid including the relative path from the build directory to the
source directory in the generated file, add a @basename@ production
variable to gimp-mkenums, which exapnds to the basename of the
input file, and use it instead of @filename@ in the recipes for the
generated enum files.
5bcde32caf