Make OpenSSL ASN.1 string types opaque for OpenSSL 4 compat (#14698)

Author: alex

src/_cffi_src/openssl/asn1.py

@@ -13,18 +13,11 @@
 
 typedef ... ASN1_INTEGER;
 
-struct asn1_string_st {
-    int length;
-    int type;
-    unsigned char *data;
-    long flags;
-};
-
-typedef struct asn1_string_st ASN1_OCTET_STRING;
-typedef struct asn1_string_st ASN1_IA5STRING;
-typedef struct asn1_string_st ASN1_TIME;
+typedef ... ASN1_OCTET_STRING;
+typedef ... ASN1_IA5STRING;
+typedef ... ASN1_TIME;
 typedef ... ASN1_OBJECT;
-typedef struct asn1_string_st ASN1_STRING;
+typedef ... ASN1_STRING;
 typedef ... ASN1_GENERALIZEDTIME;
 typedef ... ASN1_ENUMERATED;