Use -m32 on 32bit Linux

src/librustc_back/target/i686_unknown_linux_gnu.rs

@@ -11,6 +11,9 @@
 use target::Target;
 
 pub fn target() -> Target {
+    let mut base = super::linux_base::opts();
+    base.pre_link_args.push("-m32".to_string());
+
     Target {
         data_layout: "e-p:32:32-f64:32:64-i64:32:64-f80:32:32-n8:16:32".to_string(),
         llvm_target: "i686-unknown-linux-gnu".to_string(),
@@ -18,6 +21,6 @@ pub fn target() -> Target {
         target_word_size: "32".to_string(),
         arch: "x86".to_string(),
         target_os: "linux".to_string(),
-        options: super::linux_base::opts()
+        options: base,
     }
 }