"make clean && make" fails in in-tree builds.
* doc/local.mk (CLEANDIRS): Replace with...
(CLEANFILES): this safer list of files to clean.
## Graphviz examples generation. ##
## ----------------------------- ##
## Graphviz examples generation. ##
## ----------------------------- ##
+CLEANFILES += $(FIGS_GV:.gv=.eps) $(FIGS_GV:.gv=.pdf) $(FIGS_GV:.gv=.png)
FIGS_GV = \
doc/figs/example.gv \
doc/figs/example-reduce.gv doc/figs/example-shift.gv
FIGS_GV = \
doc/figs/example.gv \
doc/figs/example-reduce.gv doc/figs/example-shift.gv