ArgAbi::store: explicitly match other PassModes

Rather than using a wildcard, explicitly match against PassMode::Pair
and Direct to make it obvious how all the cases are handled.

(This is not directly related to the move annotation diff, other than to
clarify how this path works).

Author: jsgf

compiler/rustc_codegen_llvm/src/abi.rs

@@ -247,7 +247,7 @@ impl<'ll, 'tcx> ArgAbiExt<'ll, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
                 );
                 bx.lifetime_end(llscratch, scratch_size);
             }
-            _ => {
+            PassMode::Pair(..) | PassMode::Direct { .. } => {
                 OperandRef::from_immediate_or_packed_pair(bx, val, self.layout).val.store(bx, dst);
             }
         }