Move the dexfile support to implementation.

No longer require that NO_LIBDEXFILE_SUPPORT be defined or not
defined when including the header files. Move all of the different
behavior to the implementation, and keep all of the classes the
exact same whether dexfiles are supported or not.

Bug: 144470551

Test: Ran libunwindstack unit tests, libbacktrace unit tests, and
Test: debuggerd unit tests.
Test: Ran host art 137-cfi tests.
Change-Id: I4a04cfbc5d4f1bf765ef154881046c85057006c8