Remove unused error reporting code

Author: matthewjasper

src/librustc_infer/infer/error_reporting/nice_region_error/mod.rs

@@ -8,7 +8,6 @@ use rustc_span::source_map::Span;
 mod different_lifetimes;
 mod find_anon_type;
 mod named_anon_conflict;
-mod outlives_closure;
 mod placeholder_error;
 mod static_impl_trait;
 mod trait_impl_difference;
@@ -57,7 +56,6 @@ impl<'cx, 'tcx> NiceRegionError<'cx, 'tcx> {
                 ErrorReported
             })
             .or_else(|| self.try_report_anon_anon_conflict())
-            .or_else(|| self.try_report_outlives_closure())
             .or_else(|| self.try_report_static_impl_trait())
             .or_else(|| self.try_report_impl_not_conforming_to_trait())
     }