Update to improved system_properties API.

We'll now return an error if there is an actual error reading the
property, rather than treating it the same as the property not being
set.

Bug: 217728265
Test: mm
Change-Id: I81f22d9ed07443b094f9a64a0737f4d24a2afe15
diff --git a/compos/composd/src/odrefresh_task.rs b/compos/composd/src/odrefresh_task.rs
index 82eedc4..d1d0e28 100644
--- a/compos/composd/src/odrefresh_task.rs
+++ b/compos/composd/src/odrefresh_task.rs
@@ -145,9 +145,9 @@
     };
     let fd_server_raii = fd_server_config.into_fd_server()?;
 
-    let zygote_arch = system_properties::read("ro.zygote")?;
+    let zygote_arch = system_properties::read("ro.zygote")?.context("ro.zygote not set")?;
     let system_server_compiler_filter =
-        system_properties::read("dalvik.vm.systemservercompilerfilter").unwrap_or_default();
+        system_properties::read("dalvik.vm.systemservercompilerfilter")?.unwrap_or_default();
     let exit_code = service.odrefresh(
         compilation_mode,
         system_dir.as_raw_fd(),