Revert "external-sourcery-toolchain: Handle tuning libs different from toolchain libs."

This reverts commit 51ff7abb63201f7847a4dcb06f9393622edcf8d4.
tcmode: Sanity check the libdir values.

Check to make sure the values specified by the tuning file
match the system configuration.

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>