Fix fiat_test_alltoallv

[DJDavies2]

I think this fixes #80.

The problem here is that there are pointers that are becoming undefined because they are being associated with something that does not have the target attribute. This can happen like this:

integer :: a
integer, pointer :: b

call sub(a,b)

....

subroutine sub(a,b)
integer, target :: a
integer,pointer :: b
b => a
end subroutine sub

The pointer assignment in sub is valid. However when sub returns it is not valid to assume that b is associated with a in the calling routine because a does not have the target attribute in the calling rouitne; b becomes undefined.

I have added the target attributes where necessary to get this test to work.