ELF Tool Chain Code

* Add support for DWARF4 .debug_types section.
* Add new API dwarf_next_cu_header_c() which can access both compilation
units in .debug_info section and type units in .debug_types section.
* API dwarf_next_cu_header_b() is now deprecated.

Ticket: #408

Do not allocate more memory than needed.

Submitted by: jtytgat
Ticket: #433

Turn on SVN keyword expansion.

Ticket: #348

Add `$Id$` keywords.

Ticket: #348

as->as_cu_offset needs to be relocated.

Submitted by: Roman Divacky

Do not load all CUs in dwarf_init(), instead, load CU when application
calls dwarf_next_cu_header() or other APIs that require information
about a CU.

Ticket: #312

Do not load .debug_aranges section before application calls
dwarf_get_aranges().

Ticket: #312

style(9) fixes for the Copyright line.

Changes to error handling [part 2 of 2].

* Change macro `DWARF_SET_ERROR()` to take a `Dwarf_Debug` debug context
in its 1st argument. If a `Dwarf_Debug` debug context is unavailable
at the point an error has to be recorded, we use NULL. Actual error
handling is implemented by function `_dwarf_set_error()`.
* Change a few internal helper functions to take an additional Dwarf_Debug
parameter, for use with `DWARF_SET_ERROR()`.
* Replace the redundant use of `DWARF_SET_ERROR()` in `_dwarf_die_add()`
with `assert()`s; parameters `cu` and `abbrev` cannot be NULL if control
has reached this function. While we are here make the function "static".
* Use `DWARF_SET_ERROR()` consistently after a failed called to
`_dwarf_attr_find()`.

Reviewed and revised by: kaiwang27

Removed a bogus STAILQ_REMOVE.