Test a multilib setup on a 64-bit host. This is the far more common
configuration, although the test still stubs out more directories than
are necessary or common in order to exercise all of the lookup paths
observed with upstream GCC.

This finishes testing the distribution-independent and
GCC-installation-independent parts of the library path search logic.
More testing is still needed for the triple detection, GCC-installation
detection, and handling distributions with unusual configurations.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@141000 91177308-0d34-0410-b5e6-96231b3b80d8
12 files changed