Merge branch 'phony' into 'master'

Mark Makefiles that don't generate files as .PHONY

See merge request graphviz/graphviz!1361

diff --cc doc/infosrc/Makefile
index 7a749cc8e24fb2fe07f11b35c70feff7c0287f8e,0925d3f9c8e8b1da7c3a7a95488fa578bcd13eb0..a1af8cef2930fc34ef665143e2663ea900eb0d41
--- 1/doc/infosrc/Makefile
--- 2/doc/infosrc/Makefile
+++ b/doc/infosrc/Makefile
@@@ -210,9 -214,10 +213,10 @@@ $(SPLINEPNG) : mksplines.s
  clean :
        rm -f mklang sdlshapes.ps sdlshapes.ppm html.html
  
+ .PHONY: distclean
  distclean : clean
        rm -f attrs.html colors.html output.html shapes.html lang.html arrows.html
 -      rm -f $(A2GIF) $(AGIF) $(SGIF) $(MJPG) $(MGIF) $(MPNG) shapes
 +      rm -f $(A2GIF) $(AGIF) $(SGIF) $(MPJG) $(MGIF) $(MPNG) $(XGIF) shapes
        (for s in $$(cat shapelist); do rm -f $$s.gif; done)
  
  EXTRA_DIST = $(XGIF) mklang.y mkarrows.sh mkattrs.sh mkshapes.sh mkstyles.sh mktapers.sh \