Extend memory range of DexFileContainer passed to Dex loader.

Pass the whole relevant memory range (possibly including some
surrounding non-dex data).

If dex file shares data with other dex files, this will make
it possible to verify that all referred data is within bounds
of valid memory.

Test: ./art/test.py -b --host 001
Change-Id: I5e0058411db4baa3dbe74bfbd7c99d75c9afd694