Pass the current shell width to rustc

Author: estebank

src/cargo/ops/cargo_compile.rs

@@ -426,6 +426,12 @@ pub fn compile_ws<'a>(
             }
         }
     }
+    if let Some(width) = config.shell().err_width() {
+        for unit in &units {
+            bcx.extra_compiler_args
+                .insert(*unit, vec![format!("-Zterminal-width={}", width)]);
+        }
+    }
 
     let unit_dependencies = build_unit_dependencies(
         &bcx,