Make the code base clean under -Wwrite-strings.

I've also added that warning option and -Werror to the build script,
so that I'll find out if I break this property in future.

1 files changed, 2 insertions, 1 deletions

diff --git a/inertia.c b/inertia.c
index 6c64fc0..ad58bd2 100644
--- a/inertia.c
+++ b/inertia.c
@@ -738,7 +738,8 @@ static char *solve_game(const game_state *state, const game_state *currstate,
     int *unvisited;
     int circuitlen, circuitsize;
     int head, tail, pass, i, j, n, x, y, d, dd;
-    char *err, *soln, *p;
+    const char *err;
+    char *soln, *p;
 
     /*
      * Before anything else, deal with the special case in which