Expose pending hidden API warning through VMRuntime

Framework might want to show a warning message to the user when the
app has used hidden APIs. Add a JNI method through which framework
can query ART about the state of the warning flag.

Bug: 64382372
Test: make
Change-Id: I9d63db39b4d351647e6de8a64daa30c3288a5bee
1 file changed