zephyr: Make timer only available with alloc

Supporting timers requires the callback to be pinned, which requires
alloc.  It might be possible to conditionalize the code such that the
plain timer code can be used.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

zephyr/src/lib.rs

@@ -17,6 +17,7 @@ pub mod object;
 pub mod sync;
 pub mod sys;
 pub mod time;
+#[cfg(CONFIG_RUST_ALLOC)]
 pub mod timer;
 
 pub use error::{Error, Result};