Make debuggable="true" imply CheckJNI.

This should help third-party developers debug their apps.

Tested by adding logging to dalvik and launching a debuggable app.

Change-Id: Icec66825709e399e238b4ff00f2bc596485a3a60
diff --git a/services/java/com/android/server/am/ActivityManagerService.java b/services/java/com/android/server/am/ActivityManagerService.java
index f1098a8..4ec71c1 100644
--- a/services/java/com/android/server/am/ActivityManagerService.java
+++ b/services/java/com/android/server/am/ActivityManagerService.java
@@ -1933,6 +1933,9 @@
             int debugFlags = 0;
             if ((app.info.flags & ApplicationInfo.FLAG_DEBUGGABLE) != 0) {
                 debugFlags |= Zygote.DEBUG_ENABLE_DEBUGGER;
+                // Also turn on CheckJNI for debuggable apps. It's quite
+                // awkward to turn on otherwise.
+                debugFlags |= Zygote.DEBUG_ENABLE_CHECKJNI;
             }
             // Run the app in safe mode if its manifest requests so or the
             // system is booted in safe mode.