Add missing //apex_available:platform to debuggerd

This does not currently cause any problems but it does block progress
on the referenced bugs.

Bug: 187910671
Bug: 187914588
Test: m droid
Change-Id: I977cd842101187441ddbc873eac25598295aab06
diff --git a/debuggerd/proto/Android.bp b/debuggerd/proto/Android.bp
index b78224b..73cf573 100644
--- a/debuggerd/proto/Android.bp
+++ b/debuggerd/proto/Android.bp
@@ -31,6 +31,7 @@
 
     stl: "libc++_static",
     apex_available: [
+        "//apex_available:platform",
         "com.android.runtime",
     ],