package/libwebsockets: add mbedtls optional dependency

mbedtls is an optional dependency since version 2.4.0 and
https://github.com/warmcat/libwebsockets/commit/3aaf38d3d89d0436301fe66d9a5c097ea4fb1064

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/libwebsockets/libwebsockets.mk

@@ -27,9 +27,18 @@ endif
 
 ifeq ($(BR2_PACKAGE_OPENSSL),y)
 LIBWEBSOCKETS_DEPENDENCIES += openssl host-openssl
-LIBWEBSOCKETS_CONF_OPTS += -DLWS_WITH_SSL=ON
+LIBWEBSOCKETS_CONF_OPTS += \
+	-DLWS_WITH_SSL=ON \
+	-DLWS_WITH_MBEDTLS=OFF
+else ifeq ($(BR2_PACKAGE_MBEDTLS),y)
+LIBWEBSOCKETS_DEPENDENCIES += mbedtls
+LIBWEBSOCKETS_CONF_OPTS += \
+	-DLWS_WITH_SSL=ON \
+	-DLWS_WITH_MBEDTLS=ON
 else
-LIBWEBSOCKETS_CONF_OPTS += -DLWS_WITH_SSL=OFF
+LIBWEBSOCKETS_CONF_OPTS += \
+	-DLWS_WITH_SSL=OFF \
+	-DLWS_WITH_MBEDTLS=OFF
 endif
 
 ifeq ($(BR2_PACKAGE_LIBEV),y)