Patch by Christoph Reiter
https://github.com/xiph/opusfile/issues/13#issuecomment-425349836
--
diff -Nur opusfile-0.11/src/http.c opusfile-0.11-patched/src/http.c
--- opusfile-0.11/src/http.c	2018-09-14 23:25:45.000000000 +0200
+++ opusfile-0.11-patched/src/http.c	2018-09-27 15:42:55.161531800 +0200
@@ -327,10 +327,12 @@
 typedef ptrdiff_t ssize_t;
 #  endif
 
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
 /*Load certificates from the built-in certificate store.*/
 int SSL_CTX_set_default_verify_paths_win32(SSL_CTX *_ssl_ctx);
 #  define SSL_CTX_set_default_verify_paths \
  SSL_CTX_set_default_verify_paths_win32
+#endif
 
 # else
 /*Normal Berkeley sockets.*/
diff -Nur opusfile-0.11/src/wincerts.c opusfile-0.11-patched/src/wincerts.c
--- opusfile-0.11/src/wincerts.c	2017-04-22 06:01:35.000000000 +0200
+++ opusfile-0.11-patched/src/wincerts.c	2018-09-27 15:42:23.832739900 +0200
@@ -33,6 +33,8 @@
 # include <openssl/err.h>
 # include <openssl/x509.h>
 
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+
 static int op_capi_new(X509_LOOKUP *_lu){
   HCERTSTORE h_store;
   h_store=CertOpenStore(CERT_STORE_PROV_SYSTEM_A,0,0,
@@ -171,3 +173,4 @@
 }
 
 #endif
+#endif