Auto merge of #14530 - mmatyas:android_injectedglue, r=larsbergstrom

Use `android-rs-injected-glue` on Android

<!-- Please describe your changes on the following line: -->
Due to changes in `android-rs-glue`, currently the Android build fails to start. As discussed [here](https://github.com/servo/servo/issues/13154), other than the `android-glue`, we now also have to inject some additional code too. This task is usually done by a helper program of `android-glue`, `cargo-apk`, but since Servo's build system is somewhat more complex than a regular small application, at the moment it'd be more clean to move the required internal `injected-glue` lib to a new repository, and add it as a dependency.

This patch adds a new dependency, `android-rs-injected-glue`, and integrates it into Servo. After applying this commit and #14528, Servo can be launched on Android. (It doesn't *work* yet as expected, though.)

Part of #13154.

---
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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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Cargo.lock

@@ -39,6 +39,11 @@ name = "android_glue"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "android_injected_glue"
+version = "0.2.1"
+source = "git+https://github.com/mmatyas/android-rs-injected-glue#d3223d1273d0dafcf06d6a6405fedfffbf257300"
+
 [[package]]
 name = "angle"
 version = "0.1.2"
@@ -2443,6 +2448,7 @@ name = "servo"
 version = "0.0.1"
 dependencies = [
  "android_glue 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "android_injected_glue 0.2.1 (git+https://github.com/mmatyas/android-rs-injected-glue)",
  "backtrace 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "browserhtml 0.1.17 (git+https://github.com/browserhtml/browserhtml?branch=crate)",
  "compiletest_helper 0.0.1",
@@ -3277,6 +3283,7 @@ dependencies = [
 "checksum aho-corasick 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)" = "ca972c2ea5f742bfce5687b9aef75506a764f61d37f8f649047846a9686ddb66"
 "checksum alloc-no-stdlib 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b21f6ad9c9957eb5d70c3dee16d31c092b3cab339628f821766b05e6833d72b8"
 "checksum android_glue 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7e2b80445d331077679dfc6f3014f3e9ab7083e588423d35041d3fc017198189"
+"checksum android_injected_glue 0.2.1 (git+https://github.com/mmatyas/android-rs-injected-glue)" = "<none>"
 "checksum angle 0.1.2 (git+https://github.com/servo/angle?branch=servo)" = "<none>"
 "checksum app_units 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "636ee56f12e31dbc11dc0a1ac6004f08b04e6e6595963716fc8130e90d4e04cf"
 "checksum arrayvec 0.3.17 (registry+https://github.com/rust-lang/crates.io-index)" = "80a137392e2e92ce7387c063d98a11f0d47115426c5f8759657af3c7b385c860"

ports/servo/Cargo.toml

@@ -54,3 +54,4 @@ sig = "0.1"
 [target.'cfg(target_os = "android")'.dependencies]
 libc = "0.2"
 android_glue = "0.2"
+android_injected_glue = {git = "https://github.com/mmatyas/android-rs-injected-glue"}

ports/servo/main.rs

@@ -20,6 +20,8 @@
 #[cfg(target_os = "android")]
 #[macro_use]
 extern crate android_glue;
+#[cfg(target_os = "android")]
+extern crate android_injected_glue;
 extern crate backtrace;
 // The window backed by glutin
 extern crate glutin_app as app;
@@ -247,18 +249,19 @@ fn args() -> Vec<String> {
 }
 
 
-// This extern definition ensures that the linker will not discard
-// the static native lib bits, which are brought in from the NDK libraries
-// we link in from build.rs.
 #[cfg(target_os = "android")]
-extern {
-    fn app_dummy() -> libc::c_void;
+#[no_mangle]
+#[inline(never)]
+#[allow(non_snake_case)]
+pub extern "C" fn android_main(app: *mut ()) {
+    android_injected_glue::android_main2(app as *mut _, move |_, _| { main() });
 }
 
 
 #[cfg(target_os = "android")]
 mod android {
     extern crate android_glue;
+    extern crate android_injected_glue;
     extern crate libc;
 
     use self::libc::c_int;
@@ -272,7 +275,7 @@ mod android {
         redirect_output(STDERR_FILENO);
         redirect_output(STDOUT_FILENO);
 
-        unsafe { super::app_dummy(); }
+        unsafe { android_injected_glue::ffi::app_dummy() };
     }
 
     struct FilePtr(*mut self::libc::FILE);