Fix enable-zlib

The enable-zlib option was broken by the recent "const" changes.

Reviewed-by: Stephen Henson <steve@openssl.org>

crypto/cms/cms_cd.c

diff --git a/crypto/cms/cms_cd.c b/crypto/cms/cms_cd.c
index c0cb368..f05e308 100644
--- a/crypto/cms/cms_cd.c
+++ b/crypto/cms/cms_cd.c
@@ -63,7 +63,7 @@
 BIO *cms_CompressedData_init_bio(CMS_ContentInfo *cms)
 {
     CMS_CompressedData *cd;
-    ASN1_OBJECT *compoid;
+    const ASN1_OBJECT *compoid;
     if (OBJ_obj2nid(cms->contentType) != NID_id_smime_ct_compressedData) {
         CMSerr(CMS_F_CMS_COMPRESSEDDATA_INIT_BIO,
                CMS_R_CONTENT_TYPE_NOT_COMPRESSED_DATA);