eal: fix shared lib mode detection

eal: fix shared lib mode detection

Commit 06c7871dde01 ("eal: restrict default plugin path to shared lib mode")
introduced a check that enabled shared lib mode when librte_eal.so can
be loaded, 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 uses librte_eal.so.ABI_VERSION to check for shared lib,
since it exists on any linux distributions.

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

Fixes: 06c7871dde01 ("eal: restrict default plugin path to shared lib mode")
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: Ali Alnubani <alialnu@nvidia.com>