Add CBS_ASN1_UTF8STRING define.

Change-Id: I34384feb46c15c4f443f506d724ad500a4cf0f36
Reviewed-on: https://boringssl-review.googlesource.com/7525
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/include/openssl/bytestring.h b/include/openssl/bytestring.h
index cf424d0..68ede2d 100644
--- a/include/openssl/bytestring.h
+++ b/include/openssl/bytestring.h
@@ -128,6 +128,7 @@
 #define CBS_ASN1_NULL 0x5
 #define CBS_ASN1_OBJECT 0x6
 #define CBS_ASN1_ENUMERATED 0xa
+#define CBS_ASN1_UTF8STRING 0xc
 #define CBS_ASN1_SEQUENCE (0x10 | CBS_ASN1_CONSTRUCTED)
 #define CBS_ASN1_SET (0x11 | CBS_ASN1_CONSTRUCTED)
 #define CBS_ASN1_NUMERICSTRING 0x12