Don't filter empty arguments with encoded rustflags

Author: Jon Gjengset

src/cargo/core/compiler/build_context/target_info.rs

@@ -599,11 +599,10 @@ fn env_args(
     // First try CARGO_ENCODED_RUSTFLAGS from the environment.
     // Prefer this over RUSTFLAGS since it's less prone to encoding errors.
     if let Ok(a) = env::var(format!("CARGO_ENCODED_{}", name)) {
-        let args = a
-            .split('\x1f')
-            .filter(|s| !s.is_empty())
-            .map(str::to_string);
-        return Ok(args.collect());
+        if a.is_empty() {
+            return Ok(Vec::new());
+        }
+        return Ok(a.split('\x1f').map(str::to_string).collect());
     }
 
     // Then try RUSTFLAGS from the environment