eal/x86: revert select optimized memcpy at run-time

eal/x86: revert select optimized memcpy at run-time

Revert the patchset run-time Linking support including the following
3 commits:

Fixes: 84cc318424d4 ("eal/x86: select optimized memcpy at run-time")
Fixes: c7fbc80fe60f ("test: select memcpy alignment unit at run-time")
Fixes: 5f180ae32962 ("efd: move AVX2 lookup in its own compilation unit")

The patchset would cause perf drop in vhost/virtio loopback performance
test. Because the run-time dispatch must cost at least a function call
comparing to the compile-time dispatch. And the reference cpu cycles value
is small. And in the test, when using 128-256 bytes packet, it would cause
16%-20% perf drop with mergeble path. When using 256 bytes packet, it would
cause 13% perf drop with vector path.

Signed-off-by: Xiaoyun Li <xiaoyun.li@intel.com>