redlis-cli crash on non-printable chars

The debug version of isprint() raises an assert when the input value
is not EOF or in the range 0 through 0xFF, inclusive.
The trick is that the char value needs to be passed as unsigned,
before being converted to int.

src/sds.c

@@ -771,7 +771,11 @@ sds sdscatrepr(sds s, const char *p, size_t len) {
         case '\a': s = sdscatlen(s,"\\a",2); break;
         case '\b': s = sdscatlen(s,"\\b",2); break;
         default:
+#ifdef _WIN32
+            if (isprint((unsigned char)*p))
+#else
             if (isprint(*p))
+#endif
                 s = sdscatprintf(s,"%c",*p);
             else
                 s = sdscatprintf(s,"\\x%02x",(unsigned char)*p);