Also pass SYSTEMSERVERCLASSPATH to compsvc

Like the existing two, this is a temporary workaround to unblock
development, until we can run derive_classpath in the VM.

Bug: 205750213
Test: can use the variable locally
Change-Id: Ib38a0a1d22fc4528832a1abbb6a26fb9148034c7
diff --git a/compos/aidl/com/android/compos/ICompOsService.aidl b/compos/aidl/com/android/compos/ICompOsService.aidl
index 34dee54..db746fd 100644
--- a/compos/aidl/com/android/compos/ICompOsService.aidl
+++ b/compos/aidl/com/android/compos/ICompOsService.aidl
@@ -38,7 +38,8 @@
      * TODO(198211396): Implement properly. We can't simply accepting the classpaths from Android
      * since they are not derived from staged APEX (besides security reasons).
      */
-    void initializeClasspaths(String bootClasspath, String dex2oatBootClasspath);
+    void initializeClasspaths(
+            String bootClasspath, String dex2oatBootClasspath, String systemServerClassPath);
 
     /**
      * Run dex2oat command with provided args, in a context that may be specified in FdAnnotation,
diff --git a/compos/composd/src/instance_starter.rs b/compos/composd/src/instance_starter.rs
index 4b3ac1b..3e18c3e 100644
--- a/compos/composd/src/instance_starter.rs
+++ b/compos/composd/src/instance_starter.rs
@@ -152,7 +152,11 @@
 
         // TODO(198211396): Implement correctly.
         service
-            .initializeClasspaths(&env::var("BOOTCLASSPATH")?, &env::var("DEX2OATBOOTCLASSPATH")?)
+            .initializeClasspaths(
+                &env::var("BOOTCLASSPATH")?,
+                &env::var("DEX2OATBOOTCLASSPATH")?,
+                &env::var("SYSTEMSERVERCLASSPATH")?,
+            )
             .context("Initializing *CLASSPATH")?;
         Ok(())
     }
diff --git a/compos/src/compsvc.rs b/compos/src/compsvc.rs
index 2a5534c..9d2f1dc 100644
--- a/compos/src/compsvc.rs
+++ b/compos/src/compsvc.rs
@@ -90,10 +90,12 @@
         &self,
         boot_classpath: &str,
         dex2oat_boot_classpath: &str,
+        system_server_classpath: &str,
     ) -> BinderResult<()> {
         // TODO(198211396): Implement correctly.
         env::set_var("BOOTCLASSPATH", boot_classpath);
         env::set_var("DEX2OATBOOTCLASSPATH", dex2oat_boot_classpath);
+        env::set_var("SYSTEMSERVERCLASSPATH", system_server_classpath);
         Ok(())
     }