java_gen: correctly handle of_action 64-bit alignment

of_action is different from oxm in that it is 64 bit aligned,
but the alignment is contained in the length field.

Added optional parameter "length_includes_align" to the input files
to handle this situation.
diff --git a/loxi_front_end/parser.py b/loxi_front_end/parser.py
index f2cf4b0..4a465f7 100644
--- a/loxi_front_end/parser.py
+++ b/loxi_front_end/parser.py
@@ -56,7 +56,7 @@
 type_member = P.Group(tag('type') + any_type + identifier + s('==') + integer)
 data_member = P.Group(tag('data') + any_type - identifier)
 
-struct_param_name = kw("align")
+struct_param_name = kw("align") | kw("length_includes_align")
 struct_param = P.Group(struct_param_name - s('=') - word)
 struct_param_list = P.Forward()
 struct_param_list << struct_param + P.Optional(s(',') - P.Optional(struct_param_list))