Integer format can be bigger than `32` on 64bit platforms.

We made it `64` which should be big enough:
- Format modifier: 4 characters max
- Maximum width: 19 digits max
- Period between width and precision: 1 character
- Maximum precision: 19 digits max
- Format specifier: 1 character
- NUL terminator: 1 byte
- Total: 45 < 64

mrbgems/mruby-sprintf/src/sprintf.c

@@ -1041,7 +1041,7 @@ retry:
         mrb_value val = GETARG();
         double fval;
         mrb_int need = 6;
-        char fbuf[32];
+        char fbuf[64];
 
         fval = mrb_float(mrb_Float(mrb, val));
         if (!isfinite(fval)) {