cfg-gate interrupt::free to fix off-target tests

Author: adamgreig

cortex-m/src/interrupt.rs

@@ -51,6 +51,7 @@ pub unsafe fn enable() {
 /// Execute closure `f` in an interrupt-free context.
 ///
 /// This as also known as a "critical section".
+#[cfg(cortex_m)]
 #[inline]
 pub fn free<F, R>(f: F) -> R
 where
@@ -72,3 +73,12 @@ where
 
     r
 }
+
+/// No-operation included to continue presenting a `free()` method when
+/// the `cortex_m` cfg is not enabled.
+#[cfg(not(cortex_m))]
+pub fn free<F, R>(f: F) -> R
+where
+    F: FnOnce(&CriticalSection) -> R,
+{
+}

cortex-m/src/prelude.rs

@@ -1,3 +1,3 @@
 //! Prelude
 
-pub use embedded_hal::prelude::*;
+pub use eh0::prelude::*;