servo: Merge #14528 - Add C++ runtime shared object to the Android APK (from mmatyas:android_cppruntime); r=larsbergstrom

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At the moment, the Android port requires `libc++_shared.so` to run -- this patch adds the file to the generated APK.

Part of #13154.

If you know a cleaner way to solve this issue, feel free to share it! Static linking didn't work, see the related issue.

---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors

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Source-Repo: https://github.com/servo/servo
Source-Revision: 91a223093368be339ad00f42df4214ac36e1be6e

servo/support/android/build-apk/src/main.rs

@@ -17,7 +17,7 @@ fn main() {
     let (args, passthrough) = parse_arguments();
 
     // Find all the native shared libraries that exist in the target directory.
-    let native_shared_libs = find_native_libs(&args);
+    let mut native_shared_libs = find_native_libs(&args);
 
     // Get the SDK path from the ANDROID_HOME env.
     let sdk_path = env::var("ANDROID_HOME").ok().expect("Please set the ANDROID_HOME environment variable");
@@ -32,6 +32,14 @@ fn main() {
         .ok()
         .expect("Please set the ANDROID_PLATFORM environment variable");
 
+    // Add the C++ runtime .so
+    {
+        let libcpp_base_path = ndk_path.join("sources").join("cxx-stl").join("llvm-libc++").join("libs");
+        let libcpp_filename = "libc++_shared.so";
+        let libcpp_path = libcpp_base_path.join("armeabi").join(libcpp_filename);
+        native_shared_libs.insert(libcpp_filename.to_string(), libcpp_path);
+    }
+
     // Get the standalone NDK path from NDK_STANDALONE env.
     //  let standalone_path = env::var("NDK_STANDALONE").ok().unwrap_or("/opt/ndk_standalone".to_string());
     //  let standalone_path = Path::new(&standalone_path);