elfutils: remove host build from target package

elfutils: remove host build from target package

Commit f4da28c301 ("elfutils: Add host build") supplied a libelf host
library to fix a glib2 host build error, but this need was later removed
by b6212c8769 ("glib2: don't use libelf during host build").

More importantly, there are already two sources for libelf host libraries:
OpenWRT build prerequisites [1] and tools/libelf. A third is not needed.

Ref [1]: https://openwrt.org/docs/guide-developer/build-system/install-buildsystem#prerequisites

Signed-off-by: Tony Ambardar <itugrok@yahoo.com>