remove #[cfg(not(feature = unstable))] guards from z_subscriber_optio…

…ns_t

include/zenoh_commons.h

@@ -619,12 +619,10 @@ typedef struct z_queryable_options_t {
  * Options passed to the `z_declare_subscriber()` function.
  */
 typedef struct z_subscriber_options_t {
-#if !defined(UNSTABLE)
   /**
    * Dummy field to avoid having fieldless struct
    */
   uint8_t _0;
-#endif
 } z_subscriber_options_t;
 /**
  * Options passed to the `z_delete()` function.

src/subscriber.rs

@@ -50,17 +50,13 @@ pub unsafe extern "C" fn z_subscriber_loan(this_: &z_owned_subscriber_t) -> &z_l
 #[repr(C)]
 pub struct z_subscriber_options_t {
     /// Dummy field to avoid having fieldless struct
-    #[cfg(not(feature = "unstable"))]
     pub _0: u8,
 }
 
 /// Constructs the default value for `z_subscriber_options_t`.
 #[no_mangle]
 pub extern "C" fn z_subscriber_options_default(this_: &mut MaybeUninit<z_subscriber_options_t>) {
-    this_.write(z_subscriber_options_t {
-        #[cfg(not(feature = "unstable"))]
-        _0: 0,
-    });
+    this_.write(z_subscriber_options_t { _0: 0 });
 }
 
 /// Constructs and declares a subscriber for a given key expression. Dropping subscriber