Merge pull request #249 from RalfJung/rustc-target

propagate --target to rustc invocation

build.rs

@@ -71,7 +71,7 @@ fn compile_probe() -> Option<ExitStatus> {
     fs::write(&probefile, PROBE).ok()?;
 
     // Make sure to pick up Cargo rustc configuration.
-    let mut cmd = if let Some(wrapper) = env::var_os("CARGO_RUSTC_WRAPPER") {
+    let mut cmd = if let Some(wrapper) = env::var_os("RUSTC_WRAPPER") {
         let mut cmd = Command::new(wrapper);
         // The wrapper's first argument is supposed to be the path to rustc.
         cmd.arg(rustc);
@@ -89,6 +89,10 @@ fn compile_probe() -> Option<ExitStatus> {
         .arg(out_dir)
         .arg(probefile);
 
+    if let Some(target) = env::var_os("TARGET") {
+        cmd.arg("--target").arg(target);
+    }
+
     // If Cargo wants to set RUSTFLAGS, use that.
     if let Ok(rustflags) = env::var("CARGO_ENCODED_RUSTFLAGS") {
         if !rustflags.is_empty() {