Debugger: add DWARF5 attribute and form definitions

Introduce new attribute classes:
* addrptr represents an offset into the .debug_addr_section
* loclist represents an offset or an index to a location list
* rangelist represents an offset or an index to a range list
* stroffsetsptr represents an index to the indirect string table

The semantics of some existing attribute classes changed:
* loclistptr represents an offset into the
.debug_loc / .debug_loclist section
It will be used only when setting loclists_base attribute.
In all other places we should use loclist attribute class.
* rangelistptr represents an offset into the
.debug_ranges / .debug_rnglist section
It will be used only when setting rnglists_base attribute.
In all other places we should use rangelist attribute class.

Define lookup table for new DW_AT_* attribute types
* change the existing references to AC_LOCLISTPTR to AC_LOCLIST
as in those places now either an index or an offset can be accepted
(previously there were no indexes, only offsets everywhere)
* only DW_AT_loclists_base uses AC_LOCLISTPTR
* similarly for AC_RANGELISTPTR and AC_RANGELIST as ranges
can be specified using either an index or an offset
* only DW_AT_rnglists_base uses AC_RANGELISTPTR

Define lookup table for new DW_FORM_* attribute forms
* similar reshuffle for location lists and range lists

Change-Id: I78d307889cd6082a19870afdc571dc0c83d19644
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6982
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

Debugger: implement parsing DW_FORM_implicit_const

For attributes with form DW_FORM_implicit_const, the attribute
specification contains a third part which is a signed LEB128
number. This value shall be used as the value of the attribute
when parsing the debug_info section.

Change-Id: I3e9aa3ba70b3aa05e6d2f570a1464966c38e4b1b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6980
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Rene Gollent <rene@gollent.com>

Debugger: Fix various issues in the DWARF subsystem.

AttributeClasses:
- Fix typo in get_attribute_name_classes which resulted in us not
handling DW_AT_linkage_name properly.
- Fix incorrect class specification for DW_AT_default_value due
to inconsistencies in the DWARF documentation (the table of attribute
classes indicates it is only a reference, but the detailed description
indicates it also being possible to be a flag or constant, both of
which gcc outputs).

DebugInfoEntries:
- Add accessor for DIEClassBaseType's inner types.

DwarfImageDebugInfo:
- When looking up types, create a basic target interface to pass on
to the type context. Otherwise, type lookups that required DWARF
expression evaluation would crash.
- When building the type name table, we now recursively walk a class's
inner types, and add them to the list as well. This omission would
cause the debugger to lack the type description for such classes,
and consequently be unable to display their details in the variables
view.

work around "cast specifies signature type" from gcc2

...when build by gcc6 or 7 on my Debian Sid.

Debugger: Split into core library and application.

- Add subfolder src/kits/debugger which contains the debugger's core
functionality and lower layers. Correspondingly add headers/private/debugger
for shared headers to be used by clients such as the Debugger application
and eventual remote_debug_server. Adjust various files to account for
differences as a result of the split and moves.
- Add libdebugger.so to minimal Jamfile.