Bug 1083887 - Package the clang-cl runtime library for ASAN on Windows ASAN builds; r=gps
Bug 1083616 - Build on clang-cl with MSVC 2013 with fallback emulation; r=gps

We officially test MSVC2013 builds now, so it makes sense to
emulate the same compiler when building with clang-cl.  Also,
we need to build with fallback mode, since clang-cl doesn't
still support SEH.  We also need to pass these flags to NSS
too for the same reason.