Currently we use "quotearg" to escape the strings output in Dot. As a
result, if the user's locale is C for instance, all the non-ASCII are
escaped. Unfortunately graphviz does not interpret this style of
escaping.
For instance:
5 -> 2 [style=solid label="\"\303\221\303\271\341\271\203\303\251\342\204\235\303\264\""]
was displayed as a sequence of numbers. We now output:
5 -> 2 [style=solid label="\"Ñùṃéℝô\""]
independently of the user's locale.
* src/system.h (obstack_backslash): New.
* src/graphviz.h, src/graphviz.c (escape): Remove, use
obstack_backslash instead.
* src/print-graph.c: Likewise.
* tests/report.at: Adjust.