Mac OS X includes a /Library path that will cause testing.mak to incorrectly detect an Eiffel config

search for library/base instead

Signed-off-by: Reza Jelveh <reza.jelveh@tuhh.de>
cpp unit tests fail when started from testing.mak, because of case insensitivity in the file system. This patch fixes it.

Signed-off-by: Reza Jelveh <reza.jelveh@tuhh.de>