fix(pv): fix locally a division by zero occuring in Proverif

This division by zero occurs when proverif is ran from a non-TTY.

examples/default.nix

@@ -47,5 +47,10 @@ in
         sed -i "s/make -C limited-order-book/HAX_VANILLA_RUSTC=never make -C limited-order-book/g" Makefile
         make
       '';
-      buildInputs = [hax hax-env fstar jq proverif];
+      buildInputs = [
+        hax hax-env fstar jq
+        (proverif.overrideDerivation (_: {
+          patches = [ ./proverif-psk/pv_div_by_zero_fix.diff ];
+        }))
+      ];
     })

examples/proverif-psk/pv_div_by_zero_fix.diff

@@ -0,0 +1,13 @@
+diff proverif2.05/src/display.ml proverif2.05/src/display.ml
+index c43785ec..2763d907 100644
+--- proverif/src/display.ml
++++ proverif/src/display.ml
+@@ -49,7 +49,7 @@ let dynamic_display str =
+   then display_whitespace (!record_cursor_line - size);
+   (* If we cannot determine the number of columns, we just assume that the statistics
+      will fit on one line (the statistics will not be active by default) *)
+-  let lines = if columns = -1 then 0 else ((max (!record_cursor_line) size) - 1) / columns in
++  let lines = if columns <= 0 then 0 else ((max (!record_cursor_line) size) - 1) / columns in
+   (* Go to the beginning of the line *)
+   print_string "\r";
+   if lines > 0 then