elfcopy: support unordered .debug_info references to .debug_range

While trying to create shared libraries, libelfcopy complains:

libelfcopy: Error: Range lists in .debug_info section aren't in ascending order!
libelfcopy: Warning: Range lists in .debug_ranges section start at 0x60

This patch resolves by implementing the support of unordered .debug_info
references to .debug_ranges.

Inspired by Jan Kratochvil's work in binutils.

Change-Id: Ie6f8aa7fb10bb888096750247852c3e4075ce739