diff -ru cmake-3.7.2.orig/Utilities/cmlibarchive/libarchive/archive_openssl_hmac_private.h cmake-3.7.2/Utilities/cmlibarchive/libarchive/archive_openssl_hmac_private.h
--- cmake-3.7.2.orig/Utilities/cmlibarchive/libarchive/archive_openssl_hmac_private.h	2017-01-13 15:05:42.000000000 +0100
+++ cmake-3.7.2/Utilities/cmlibarchive/libarchive/archive_openssl_hmac_private.h	2018-05-08 22:39:23.249070904 +0200
@@ -28,7 +28,8 @@
 #include <openssl/hmac.h>
 #include <openssl/opensslv.h>
 
-#if OPENSSL_VERSION_NUMBER < 0x10100000L
+#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
+    (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x2070000fL)
 #include <stdlib.h> /* malloc, free */
 #include <string.h> /* memset */
 static inline HMAC_CTX *HMAC_CTX_new(void)