ADD - IntoDiagnostic conformance for TargetDataLayoutErrors in rustc_errors

This way we comply with the Coherence rule given that IntoDiagnostic trait is defined in rustc_errors, and almost all other crates depend on it.

compiler/rustc_errors/src/lib.rs

@@ -51,6 +51,7 @@ use termcolor::{Color, ColorSpec};
 pub mod annotate_snippet_emitter_writer;
 mod diagnostic;
 mod diagnostic_builder;
+mod diagnostic_impls;
 pub mod emitter;
 pub mod json;
 mod lock;