Allow some lints that only fired on 32-bit and/or Windows.

src/test/run-pass/process/process-sigpipe.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 // run-pass
+#![allow(unused_imports)]
 #![allow(deprecated)]
 
 // ignore-android since the dynamic linker sets a SIGPIPE handler (to do

src/test/run-pass/structs-enums/struct-return.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 // run-pass
+#![allow(dead_code)]
 // ignore-wasm32-bare no libc to test ffi with
 
 #[repr(C)]