Move linker flags to build script.

tests/riscv32/.cargo/config.toml

@@ -1,9 +1,5 @@
 [target.riscv32imac-unknown-none-elf]
 runner = "true"
-rustflags = [
-  "-C", "link-arg=-Tmemory.x",
-  "-C", "link-arg=-Tlink.x",
-]
 
 [build]
 target = "riscv32imac-unknown-none-elf"

tests/riscv32/build.rs

@@ -0,0 +1,8 @@
+use std::error::Error;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    println!("cargo:rustc-link-arg-bins=-Tmemory.x");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
+
+    Ok(())
+}