debuginfo: Change C++-like encoding for enums.

The updated encoding should be able to handle niche layouts where
more than one variant has fields.

Author: michaelwoerister

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -114,6 +114,7 @@ macro_rules! return_if_di_node_created_in_meantime {
 }
 
 /// Extract size and alignment from a TyAndLayout.
+#[inline]
 fn size_and_align_of<'tcx>(ty_and_layout: TyAndLayout<'tcx>) -> (Size, Align) {
     (ty_and_layout.size, ty_and_layout.align.abi)
 }