Label r.colors.tmp.html as an intermediate file

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@39165 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.colors/Makefile

@@ -24,3 +24,4 @@ $(BIN)/r.mapcalc$(EXE):
 
 .PHONY: thumbnails
 
+.INTERMEDIATE: r.colors.tmp.html