fix #1249 - potential race with make -j 		Martin von Gagern <Martin.vGagern@gmx.net>
fix #1249 - potential race with make -j
		Martin von Gagern <Martin.vGagern@gmx.net>

jho1965us/graphviz,pixelglow/graphviz,jho1965us/graphviz,MjAbuz/graphviz,ellson/graphviz,tkelman/graphviz,jho1965us/graphviz,BMJHayward/graphviz,kbrock/graphviz,ellson/graphviz,pixelglow/graphviz,kbrock/graphviz,pixelglow/graphviz,pixelglow/graphviz,jho1965us/graphviz,BMJHayward/graphviz,tkelman/graphviz,kbrock/graphviz,ellson/graphviz,kbrock/graphviz,ellson/graphviz,kbrock/graphviz,tkelman/graphviz,BMJHayward/graphviz,MjAbuz/graphviz,ellson/graphviz,pixelglow/graphviz,kbrock/graphviz,jho1965us/graphviz,BMJHayward/graphviz,ellson/graphviz,jho1965us/graphviz,MjAbuz/graphviz,kbrock/graphviz,BMJHayward/graphviz,jho1965us/graphviz,MjAbuz/graphviz,ellson/graphviz,jho1965us/graphviz,BMJHayward/graphviz,ellson/graphviz,jho1965us/graphviz,MjAbuz/graphviz,ellson/graphviz,tkelman/graphviz,BMJHayward/graphviz,BMJHayward/graphviz,pixelglow/graphviz,MjAbuz/graphviz,BMJHayward/graphviz,ellson/graphviz,ellson/graphviz,tkelman/graphviz,kbrock/graphviz,tkelman/graphviz,pixelglow/graphviz,kbrock/graphviz,tkelman/graphviz,kbrock/graphviz,MjAbuz/graphviz,MjAbuz/graphviz,pixelglow/graphviz,tkelman/graphviz,BMJHayward/graphviz,pixelglow/graphviz,tkelman/graphviz,pixelglow/graphviz,MjAbuz/graphviz,jho1965us/graphviz,MjAbuz/graphviz,MjAbuz/graphviz,tkelman/graphviz,tkelman/graphviz,BMJHayward/graphviz,pixelglow/graphviz,jho1965us/graphviz,kbrock/graphviz