[ruby/openssl] asn1: make ossl_asn1_get_asn1type() private

The function is not used anywhere outside of ossl_asn1.c.

https://github.com/ruby/openssl/commit/5392b79941

ext/openssl/ossl_asn1.c

@@ -497,7 +497,7 @@ static VALUE class_tag_map;
 
 static int ossl_asn1_default_tag(VALUE obj);
 
-ASN1_TYPE*
+static ASN1_TYPE *
 ossl_asn1_get_asn1type(VALUE obj)
 {
     ASN1_TYPE *ret;

ext/openssl/ossl_asn1.h

@@ -57,8 +57,6 @@ extern VALUE cASN1Sequence, cASN1Set;                /* CONSTRUCTIVE      */
 
 extern VALUE cASN1EndOfContent;                      /* END OF CONTENT      */
 
-ASN1_TYPE *ossl_asn1_get_asn1type(VALUE);
-
 void Init_ossl_asn1(void);
 
 #endif