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

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!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126760 91177308-0d34-0410-b5e6-96231b3b80d8