Fix fastsearch for UCS2 and UCS4
* If needle is 0, try (p[0] >> 16) & 0xff for UCS4
* Disable fastsearch_memchr_1char() if needle is zero for UCS2 and UCS4
diff --git a/Objects/stringlib/stringdefs.h b/Objects/stringlib/stringdefs.h
index 9619332..41449fc 100644
--- a/Objects/stringlib/stringdefs.h
+++ b/Objects/stringlib/stringdefs.h
@@ -9,6 +9,7 @@
#define FASTSEARCH fastsearch
#define STRINGLIB(F) stringlib_##F
#define STRINGLIB_OBJECT PyBytesObject
+#define STRINGLIB_SIZEOF_CHAR 1
#define STRINGLIB_CHAR char
#define STRINGLIB_TYPE_NAME "string"
#define STRINGLIB_PARSE_CODE "S"