message: Simplify unused build scripts in tests
  The tests in question all tail to even build the build script, so the
  contents of `main` don't matter, and make the tests seem more complex
  than they really are.
diff: @@ -355,16 +355,7 @@ fn custom_build_env_var_rustc_linker_bad_host_target() {
  target
  ),
  )
  - .file(
  - "build.rs",
  - r#"
  - use std::env;
  -
  - fn main() {
  - assert!(env::var("RUSTC_LINKER").unwrap().ends_with("/path/to/linker"));
  - }
  - "#,
  - )
  + .file("build.rs", "fn main() {}")
  .file("src/lib.rs", "")
  .build();
  @@ -467,16 +458,7 @@ fn custom_build_invalid_host_config_feature_flag() {
  target
  ),
  )
  - .file(
  - "build.rs",
  - r#"
  - use std::env;
  -
  - fn main() {
  - assert!(env::var("RUSTC_LINKER").unwrap().ends_with("/path/to/linker"));
  - }
  - "#,
  - )
  + .file("build.rs", "fn main() {}")
  .file("src/lib.rs", "")
  .build();
  @@ -510,16 +492,7 @@ fn custom_build_env_var_rustc_linker_host_target_with_bad_host_config() {
  target
  ),
  )
  - .file(
  - "build.rs",
  - r#"
  - use std::env;
  -
  - fn main() {
  - assert!(env::var("RUSTC_LINKER").unwrap().ends_with("/path/to/target/linker"));
  - }
  - "#,
  - )
  + .file("build.rs", "fn main() {}")
  .file("src/lib.rs", "")
  .build();
  @@ -554,16 +527,7 @@ fn custom_build_env_var_rustc_linker_bad_host() {
  target
  ),
  )
  - .file(
  - "build.rs",
  - r#"
  - use std::env;
  -
  - fn main() {
  - assert!(env::var("RUSTC_LINKER").unwrap().ends_with("/path/to/target/linker"));
  - }
  - "#,
  - )
  + .file("build.rs", "fn main() {}")
  .file("src/lib.rs", "")
  .build();
  @@ -600,16 +564,7 @@ fn custom_build_env_var_rustc_linker_bad_host_with_arch() {
  target, target
  ),
  )
  - .file(
  - "build.rs",
  - r#"
  - use std::env;
  -
  - fn main() {
  - assert!(env::var("RUSTC_LINKER").unwrap().ends_with("/path/to/target/linker"));
  - }
  - "#,
  - )
  + .file("build.rs", "fn main() {}")
  .file("src/lib.rs", "")
  .build();
  @@ -658,7 +613,8 @@ fn custom_build_env_var_rustc_linker_cross_arch_host() {
  .file("src/lib.rs", "")
  .build();
  - // build.rs should fail due to bad host linker being set
  + // build.rs should be built fine since cross target != host target.
  + // assertion should succeed since it's still passed the target linker
  p.cargo("build -Z target-applies-to-host -Z host-config --verbose --target")
  .arg(&target)
  .masquerade_as_nightly_cargo()
  @@ -684,16 +640,7 @@ fn custom_build_env_var_rustc_linker_bad_cross_arch_host() {
  cross_target, target
  ),
  )
  - .file(
  - "build.rs",
  - r#"
  - use std::env;
  -
  - fn main() {
  - assert!(env::var("RUSTC_LINKER").unwrap().ends_with("/path/to/target/linker"));
  - }
  - "#,
  - )
  + .file("build.rs", "fn main() {}")
  .file("src/lib.rs", "")
  .build();
  