package/nginx: fix mail modules not building

Add the missing --with-mail configure option

Signed-off-by: Martin Bark <martin@barkynet.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/nginx/nginx.mk

@@ -193,6 +193,7 @@ endif # BR2_PACKAGE_NGINX_HTTP
 
 # mail modules
 ifeq ($(BR2_PACKAGE_NGINX_MAIL),y)
+NGINX_CONF_OPTS += --with-mail
 
 ifeq ($(BR2_PACKAGE_NGINX_MAIL_SSL_MODULE),y)
 NGINX_DEPENDENCIES += openssl