Migrated dexdump from Dalvik (libdex) into Art (libart)

Rationale:
The new dexdump (temporarily called dexdump2 until we are
satisfied with the migration) is a re-implementation of the
original dexdump utility that was based on Dalvik functions
in libdex into a new dexdump that is now based on Art functions
in libart instead.

The output is identical to the original for *correct* DEX files.
Output in error messages and the usage() may differ, however,
since the new utility relies on Art parsing and verification.

NOTE 1:
ODEX files are no longer supported.

NOTE 2:
Where possible, I kept the file as close to the original
as possible, including some archaic C idioms on memory
allocation; those can be improved over time.

NOTE 3:
I used the standard Android.mk format for the new dexdump,
but this probably needs to be Art-i-fied.

NOTE 4:
Some minor issues that need resolution are marked with a TODO.

Bug: 17442393
Change-Id: I753743f64afcf4b84b8d33efbd1cfcb7908f0c3e