Move verbose proof-of-work/target comparison display into -D (debug)

util.c

@@ -283,6 +283,7 @@ bool fulltest(const unsigned char *hash, const unsigned char *target)
 		}
 	}
 
+	if (opt_debug) {
 		hash_str = bin2hex(hash_swap, 32);
 		target_str = bin2hex(target_swap, 32);
 
@@ -294,6 +295,7 @@ bool fulltest(const unsigned char *hash, const unsigned char *target)
 
 		free(hash_str);
 		free(target_str);
+	}
 
 	return rc;
 }