Add lib_exports.sh for printing list of exported functions.

Prints the list of exported functions from a built library object.
Useful for sanity checking.

lib_exports.sh

+#!/bin/sh
+# Print public API (ground truth list of functions exported from the built library)
+readelf -W --dyn-syms "$(dirname "$0")"/build/libolm.so | grep -v UND | grep olm_ | awk '{ print $8 }' | sort -u