graphviz: Do not require libltdl.la for building

packages/graphviz/configure.patch

@@ -0,0 +1,21 @@
+Do not require libltdl.la for building.
+
+diff -u -r ../graphviz-2.40.1/configure ./configure
+--- ../graphviz-2.40.1/configure	2016-12-25 04:04:52.000000000 +0100
++++ ./configure	2017-08-11 14:35:43.459379008 +0200
+@@ -19556,15 +19556,6 @@
+ fi
+ 
+ 
+-if test -n "$with_ltdl_lib"; then
+-  if test -f "$with_ltdl_lib/libltdl.la"; then :
+-  else
+-    as_fn_error $? "invalid ltdl library directory: \`$with_ltdl_lib'" "$LINENO" 5
+-  fi
+-else
+-  with_ltdl_lib=no
+-fi
+-
+ case ,$with_included_ltdl,$with_ltdl_include,$with_ltdl_lib, in
+   ,yes,no,no,)
+ 	case $enable_ltdl_convenience in