Remove likely brittle test.

This is too dependent on the particulars of libstd.

tests/build-std/main.rs

@@ -211,59 +211,3 @@ fn custom_test_framework() {
         .build_std_arg("core")
         .run();
 }
-
-#[cargo_test(build_std)]
-fn common_crate_collision() {
-    // Check for collision with `cc` crate in build dependencies.
-    // This needs to be a full test since we need to use the real `cc` crate.
-    // This is a bit fragile, since it assumes `cc` is used in libstd,
-    // and that we are selecting the same features.
-
-    // Determine the version of CC used in the real std so that we use the
-    // exact same version.
-    let sysroot = paths::sysroot();
-    let sysroot = Path::new(&sysroot);
-    let contents =
-        std::fs::read_to_string(sysroot.join("lib/rustlib/src/rust/Cargo.lock")).unwrap();
-    let lock: toml::Value = toml::from_str(&contents).unwrap();
-    let mut packages = lock["package"].as_array().unwrap().iter();
-    let cc = packages
-        .find(|p| p["name"].as_str().unwrap() == "cc")
-        .unwrap();
-    // Make sure there is only one `cc`.
-    assert!(packages
-        .find(|p| p["name"].as_str().unwrap() == "cc")
-        .is_none());
-    let cc_version = cc["version"].as_str().unwrap();
-
-    let p = project()
-        .file(
-            "Cargo.toml",
-            &format!(
-                r#"
-                [package]
-                name = "foo"
-                version = "0.1.0"
-
-                [build-dependencies]
-                cc = "={}"
-                "#,
-                cc_version
-            ),
-        )
-        .file("build.rs", "extern crate cc; fn main() {}")
-        .file("src/main.rs", "fn main() {}")
-        .build();
-
-    p.cargo("build -v")
-        .build_std()
-        .target_host()
-        .with_stderr_contains(
-            "[RUNNING] `rustc --crate-name cc [..]-Zforce-unstable-if-unmarked[..]",
-        )
-        .with_stderr_line_without(
-            &["[RUNNING] `rustc --crate-name cc"],
-            &["-Zforce-unstable-if-unmarked"],
-        )
-        .run();
-}