replace all uses of log with tracing

crates/wiggle/src/lib.rs

@@ -15,6 +15,7 @@ mod borrow;
 mod error;
 mod guest_type;
 mod region;
+pub mod tracing;
 
 pub use borrow::BorrowChecker;
 use borrow::BorrowHandle;

crates/wiggle/src/tracing.rs

@@ -0,0 +1,11 @@
+#[cfg(feature = "tracing")]
+pub use tracing_crate::*;
+
+#[cfg(not(feature = "tracing"))]
+mod noop_tracing {
+    // TODO fill in rest of the noop interface
+    // idk how to do this because macro_rules! / #[macro_export] doesn't follow the usual module
+    // visibility rules.
+}
+#[cfg(not(feature = "tracing"))]
+pub use noop_tracing::*;