php-yaml: re add package, now compatible with PHP 7

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
diff --git a/package/Config.in b/package/Config.in
index 4639587..ae74f17 100644
--- a/package/Config.in
+++ b/package/Config.in
@@ -618,6 +618,7 @@
 	source "package/php-imagick/Config.in"
 	source "package/php-memcached/Config.in"
 	source "package/php-ssh2/Config.in"
+	source "package/php-yaml/Config.in"
 	source "package/php-zmq/Config.in"
 endmenu
 endif