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, 1 insertions, 1 deletions

diff --git a/blackbox.c b/blackbox.c
index 829aaec..d92af92 100644
--- a/blackbox.c
+++ b/blackbox.c
@@ -251,7 +251,7 @@ static const char *validate_desc(const game_params *params, const char *desc)
 {
     int nballs, dlen = strlen(desc), i;
     unsigned char *bmp;
-    char *ret;
+    const char *ret;
 
     /* the bitmap is 2+(nballs*2) long; the hex version is double that. */
     nballs = ((dlen/2)-2)/2;