Add option to identify primary zygote.

This will be used to customize when to start pre-jitting in
jitzygote mode.

Test: boots
Bug: 119800099
Change-Id: I1b5c1c454455d336f22e3328deead4ced1742239
diff --git a/runtime/runtime.h b/runtime/runtime.h
index c4baf40..dd66b85 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -163,6 +163,10 @@
     return is_zygote_;
   }
 
+  bool IsPrimaryZygote() const {
+    return is_primary_zygote_;
+  }
+
   bool IsSystemServer() const {
     return is_system_server_;
   }
@@ -944,6 +948,7 @@
 
   CompilerCallbacks* compiler_callbacks_;
   bool is_zygote_;
+  bool is_primary_zygote_;
   bool is_system_server_;
   bool must_relocate_;
   bool is_concurrent_gc_enabled_;