Allow [CCode (has_construct_function = false)] to be used for non-bindings
Submitted by Philip Withnall
As discussed on IRC, it would be nice if
[CCode (has_construct_function = false)] could be used in normal Vala code to stop Vala generating
*_construct() functions for objects. This would allow the C API of Vala libraries to be neatened up (at the cost of making the objects potentially inextensible).