explicitly mark unused variables found by pylint with _ or dummy

pylint don't ignores unused variables with '_' in the name, even when
they are started with '_'. This bug is already fixed upstream, to fix
this in all versions of pylint custom dummy-variables-rgx is used
'_+$|(_[a-zA-Z0-9_]*[a-zA-Z0-9]+?$)|dummy'

#! gmake

yml := ../../yml2
ysl2files := $(wildcard *.ysl2)
xsltfiles := $(patsubst %.ysl2, %.xslt, $(ysl2files))

all:$(xsltfiles)

%.xslt: %.ysl2
	$(yml)/yml2c -I $(yml) $< -o $@.tmp
	xmlstarlet fo $@.tmp > $@
	rm $@.tmp
	
clean:
	rm -f $(xsltfiles)