apk: Use rustc --crate-type=cdylib to always force a lib to be compiled

This automatically turns `crate-type = ["lib"]` and `[lib]` targets into
a `cdylib`, and otherwise errors when it encounters a binary.

Author: MarijnS95

cargo-apk/src/apk.rs

@@ -226,7 +226,8 @@ impl<'a> ApkBuilder<'a> {
                 self.min_sdk_version(),
                 self.cmd.target_dir(),
             )?;
-            cargo.arg("build");
+            cargo.arg("rustc");
+            cargo.arg("--crate-type=cdylib");
             if self.cmd.target().is_none() {
                 cargo.arg("--target").arg(triple);
             }