The DWARF v5 Spec describes a (slightly) new format for V5 .dwp files.
This patch updates GDB to allow it to read/process .dwp files in the
new DWARF v5 format, while continuing to be able to read/process .dwp
files in the older V1 & V2 formats.

The one thing I felt a little odd about in this patch:  I couldn't
re-use the enum dwarf_sect
definitions, because  in version 5 several of the sections have the
same name as in the previous versions, but have a different ordering,
with different numbers attached.  So I had to create a new enum,
dwarf_sect_v5 for this purpose.

Is this patch ok to commit?

-- Caroline
cmtice@google.com

gdb/ChangeLog

2020-07-20  Caroline Tice  <cmtice@google.com>

        * dwarf2/read.c (struct dwo_file): Update comment on 'sections' field.
        (struct dwp_sections): Update field comments.  Add loclists and
        rnglists fields.
        (struct virtual_v2_dwo_sections): Rename struct to
        'virtual_v2_or_v5_dwo_sections'; update comments at top of struct; add
        size & offset fields for loclists and rnglists.
        (struct dwp_hash_table): Add a 'v5' struct field to the union section.
        (create_dwp_hash_table):  Update the large comment above the function to
        discuss Version 5 DWP files as well.  Update all the version checks in
        the function to check for version 5 as well.  Add new section at the
        end to create dwp hash table for version 5.
        (create_dwp_v2_section): Rename function to
        'create_dwp_v2_or_v5_section'.  Update function comment appropriately.
        Add V5 to error message text.
        (create_dwo_unit_in_dwp_v2): Change calls to create_cwp_v2_section
        into calls to create_dwp_v2_or_v5_section.
        (create_dwo_unit_in_dwp_v5): New function.
        (lookup_dwo_unit_in_dwp): Update conditional statement to explicitly
        check for version2; add else clause to handle version 5.
        (dwarf2_locate_v2_dwp_sections): Update function comment to mention
        version 5.
        (dwarf2_locate_v5_dwp_sections): New function.
        (open_and_init_dwp_file): Add else-if clause for version 5 to call
        bfd_map_over_sections with dwarf2_locate_v5_dwp_sections.

include/ChangeLog

2020-07-20  Caroline Tice  <cmtice@google.com>

        * dwarf2.h (enum dwarf_sect_v5): A new enum section for the
        sections in a DWARF 5 DWP file (DWP version 5).