ExifInterface: Prevent infinite loop

A corrupted image file may create two problems.
1. A corrupted IFD pointer may point to an IFD that has already
been read, thus creating an infinite loop and a stack overflow.
2. A corrupted IFD offset value may have a negative value, thus
prompting a random reading of the file and creating an infinite
loop.
This CL addresses these issues.

Bug: 63800695
Test: Run cts (ExifInterfaceTest)
Change-Id: I706a0c3eae6af8301af69407333ea88e5681df3c