elfutils: import package from packages.git

elfutils is required by perf. So we'll move this package from
packages.git and make it part of the core distribution.

Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45969 3c298f89-4303-0410-b956-a3cf2f4a3e73