auto merge of #6400 : cmr/rust/remove_useless_import_error, r=thestinger

Every unresolved import is reported. An additional error message isn't useful
and obscures (imo) the real errors: I need to take it into account when
looking at the error count.

src/test/compile-fail/issue-2937.rs

@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// error-pattern:failed to resolve imports
-use x = m::f;
+use x = m::f; //~ ERROR failed to resolve import
 
 mod m {
 }