Revert "iproute2: simplify linking libelf for eBFP/XDP object file support"

This reverts commit 26681fa6a6 as it breaks the
installation of the iproute2 utilities ip-bridge, ss, nstat, devlink and rdma
for the ip-full variant

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

package/network/utils/iproute2/patches/145-keep_libelf_optional.patch

@@ -1,11 +0,0 @@
---- a/configure
-+++ b/configure
-@@ -228,7 +228,7 @@ EOF
- 
- check_elf()
- {
--    if ${PKG_CONFIG} libelf --exists; then
-+    if [ "${HAVE_ELF}" = "y" ] && ${PKG_CONFIG} libelf --exists; then
- 	echo "HAVE_ELF:=y" >>$CONFIG
- 	echo "yes"
-