BUILD: ssl: switch LibreSSL to Fastly CDN

OpenBSD ftp is down, let us switch to CDN
diff --git a/scripts/build-ssl.sh b/scripts/build-ssl.sh
index 4360adf..a1935dd 100755
--- a/scripts/build-ssl.sh
+++ b/scripts/build-ssl.sh
@@ -59,7 +59,7 @@
 download_libressl () {
     if [ ! -f "download-cache/libressl-${LIBRESSL_VERSION}.tar.gz" ]; then
         wget -P download-cache/ \
-	    "https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-${LIBRESSL_VERSION}.tar.gz"
+	    "https://cdn.openbsd.org/pub/OpenBSD/LibreSSL/libressl-${LIBRESSL_VERSION}.tar.gz"
     fi
 }