On FreeBSD, we don't want 'getDriver().Dir + "/../lib"' added to the

ToolChain's FilePaths.  If clang is installed as a port in /usr/local,
it is *not* supposed to use /usr/local/lib by default, for example.

Additionally, there are no clang-related executables in either
/usr/libexec, or getDriver().Dir + "/../libexec", anymore, so remove
that from the ToolChain's ProgramPaths.

Patch by Dimitry Andric!

llvm-svn: 126760