testrunner: fixed failure to find libs when invoked via bin/ symlink
testrunner: fixed failure to find libs when invoked via bin/ symlink

Currently we use a path relative to $FindBin::Bin to find our own
libraries.  This was broken when testrunner.pl was invoked via the
symlink in the bin/ directory.  Make it work in both cases.

Change-Id: I14ab52df761dda9cf6a99c09fc39fac61a71ea74
Reviewed-by: Kalle Lehtonen <d0f4e666f912516036887a48f8b9d9fc5a6f6350@nokia.com>

tsarajar/qtqa,tsarajar/qtqa,tsarajar/qtqa,tsarajar/qtqa