elfutils: add PACKAGECONFIG for compression algorithms

elfutils: add PACKAGECONFIG for compression algorithms

Elfutils has optional support for bzip2 and xz (lzma). It uses
this for decompressing embedded ELF sections like the .gnu_debugdata
section for "mini debuginfo":

https://sourceware.org/gdb/onlinedocs/gdb/MiniDebugInfo.html

Previously this support was unconditionally disabled but the reasons for
disabling them seem to no longer apply. Both the target and native
variants of elfutils can build successfully against both bzip2 and xz.

Signed-off-by: Dan Callaghan <dan.callaghan@opengear.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>