[PATCH] msvcp: Add a stub of _Concurrent_vector_base_v4.

[Alex Henrie]

The patch looks mostly correct to me, but I'm getting compiler errors with
`./configure --enable-win64 && make`:

msvcp110.spec:480: function '_Concurrent_vector_vase_v4_dtor' not defined
msvcp110.spec:1499: function '_Concurrent_vector_vase_v4__Internal_copy'
not defined

-Alex