eal: fix plugin loading

eal: fix plugin loading

Commit 49b536fc3060 ("eal: load only shared libs from driver plugin directories")
introduced a check that any shared library must ends with .so, but it can't
work, at least, on Fedora/CentOS/RHEL since .so symlinks are not installed
when you install dpdk package, but only when you install dpdk-devel package.

This commit adds also a check for .so.ABI_VERSION to check for shared lib.

See Fedora Packaging Guidelines for more information:
https://docs.fedoraproject.org/en-US/packaging-guidelines/#_devel_packages

Fixes: 49b536fc3060 ("eal: load only shared libs from driver plugin directories")
Cc: stable@dpdk.org
Signed-off-by: Timothy Redaelli <tredaelli@redhat.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: David Marchand <david.marchand@redhat.com>
Acked-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Tested-by: Ferruh Yigit <ferruh.yigit@intel.com>
Tested-by: Ali Alnubani <alialnu@nvidia.com>