Remove trap registration from wasmtime crate (#903)

Our trampoline shims no longer have traps baked into them so this is
largely all dead code now at this point.

crates/jit/src/trampoline.rs

@@ -10,6 +10,7 @@ pub use cranelift_codegen::Context;
 pub use cranelift_frontend::{FunctionBuilder, FunctionBuilderContext};
 
 pub mod binemit {
+    pub use cranelift_codegen::binemit::NullTrapSink;
     pub use cranelift_codegen::binemit::{CodeOffset, NullStackmapSink, TrapSink};
 
     use cranelift_codegen::{binemit, ir};