Relocate DWARF using .oat_patches.

The current solution is to hard-code knowledge of DWARF in the linker.
This works for simple use of DWARF, but breaks as soon as I try to do
anything more complex.  Making the linker fully support DWARF would be
non-trivial task and would be essentially rewrite.  Using .oat_patches
is much easier solution.

Relocating .debug_* sections required extending .oat_patches to support
more sections than just .text.  I have encoded each section as
null-terminated section name followed by ULEB128 deltas.

The ULEB128 encoding shrinks .oat_patches for .text by factor of
about 6 with 64-bit compiler, and factor of 3 with 32-bit compiler.

On the other hand, it grows by the extra .oat_patches for DWARF which
were not present before (if debug symbols are included).

Overall, it is still a clear improvement even with the DWARF patches.

Change-Id: I78ffeda0f8a3da03341995a3b5ef15c954e16e9f