Try to mmap vdex file within the address range of the ELF file.

Add ELF section for the vdex file and mmap it there at runtime.
This ensures that the data is at predictable location, which
is needed to be able to reference it from native debug-info.

This does not change the amount of memory allocated, or the
location of the data on disk.  However, it does change how
the memory is allocated - it replaces two allocations
(ELF and vdex) by just one (ELF which includes the vdex).

Bug: 71579677
Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing

Change-Id: Ie2abd36c8b6617a527368e71f932998bbe5ad38c