Spellchecking compiler comments

This PR cleans up the rest of the spelling mistakes in the compiler comments. This PR does not change any literal or code spelling issues.

compiler/rustc_monomorphize/src/partitioning/default.rs

@@ -501,7 +501,7 @@ fn mono_item_visibility<'tcx>(
         // * First is weak lang items. These are basically mechanisms for
         //   libcore to forward-reference symbols defined later in crates like
         //   the standard library or `#[panic_handler]` definitions. The
-        //   definition of these weak lang items needs to be referenceable by
+        //   definition of these weak lang items needs to be referencable by
         //   libcore, so we're no longer a candidate for internalization.
         //   Removal of these functions can't be done by LLVM but rather must be
         //   done by the linker as it's a non-local decision.

compiler/rustc_monomorphize/src/polymorphize.rs

@@ -65,7 +65,7 @@ fn unused_generic_params<'tcx>(
     mark_used_by_default_parameters(tcx, def_id, generics, &mut unused_parameters);
     debug!(?unused_parameters, "(after default)");
 
-    // Visit MIR and accumululate used generic parameters.
+    // Visit MIR and accumulate used generic parameters.
     let body = match tcx.hir().body_const_context(def_id.expect_local()) {
         // Const functions are actually called and should thus be considered for polymorphization
         // via their runtime MIR.