Move annotations to native.

Art side of this change. There is also a corresponding Libcore change.

Seeing ~2-3x speedup over dalvik KK MR1 in AnnotatedElementBenchmark.
Benchmark			 Speedup of Art AOSP to Dalvik KK MR1
GetAllReturnsLargeAnnotation	 2.99
GetAllReturnsMarkerAnnotation	 2.20
GetAllReturnsNoAnnotation	 2.43
GetAllReturnsSmallAnnotation	 2.52
GetAllReturnsThreeAnnotations	 2.87
GetAnnotationsOnSubclass	 2.42
GetDeclaredAnnotationsOnSubclass 2.49
GetFieldAnnotation		 2.68
GetFieldAnnotations		 2.60
GetMethodAnnotation		 2.66
GetMethodAnnotations		 2.61
GetParameterAnnotations		 2.52
GetTypeAnnotation		 2.56
GetTypeAnnotations		 2.17
IsFieldAnnotationPresent	 3.26
IsMethodAnnotationPresent	 4.99
IsTypeAnnotationPresent		 1.34

Change-Id: Ibdbb6d23b17eaab6e83c8774b1bb9401e8227941