Simplify a provider definition.

Author: nnethercote

compiler/rustc_mir_transform/src/lib.rs

@@ -127,7 +127,7 @@ pub fn provide(providers: &mut Providers) {
         mir_coroutine_witnesses: coroutine::mir_coroutine_witnesses,
         optimized_mir,
         is_mir_available,
-        is_ctfe_mir_available: |tcx, did| is_mir_available(tcx, did),
+        is_ctfe_mir_available: is_mir_available,
         mir_callgraph_reachable: inline::cycle::mir_callgraph_reachable,
         mir_inliner_callees: inline::cycle::mir_inliner_callees,
         promoted_mir,