message: tests/cfg: allow unused extern crates
diff: @@ -208,7 +208,7 @@ fn works_through_the_registry() {
  [dependencies]
  bar = "0.1.0"
  "#)
  - .file("src/lib.rs", "extern crate bar;");
  + .file("src/lib.rs", "#[allow(unused_extern_crates)] extern crate bar;");
  assert_that(p.cargo_process("build"),
  execs().with_status(0).with_stderr("\
  @@ -242,7 +242,7 @@ fn ignore_version_from_other_platform() {
  [target.'cfg({})'.dependencies]
  foo = "0.2.0"
  "#, this_family, other_family))
  - .file("src/lib.rs", "extern crate foo;");
  + .file("src/lib.rs", "#[allow(unused_extern_crates)] extern crate foo;");
  assert_that(p.cargo_process("build"),
  execs().with_status(0).with_stderr("\
  