Some gimprc properties' default values depend on the machine where
"make dist" in run. We had an ugly hack in place to force
(num-processors 1) in the installed system gimprc and its manpage, but
were still leaking "tile-cache-size" and "mypaint-brush-path".
The files are generated by the hidden options --dump-gimprc-system
and --dump-gimprc-manpage which exist only for this purpose.
In gimpconfig-dump.c, special case the three properties in
dump_gimprc_system() and dump_gimprc_manpage() to output constant
default values for "num-processors" and "tile-cache-size" and
output @mypaint_brushes_dir@ in "mypaint-brush-path" which can
be replaced at configure time.
Also introduce etc/gimprc.in so @mypaint_brushes_dir@ can actually be
substituted for the installed system gimprc.
Michael Natterer