Don't pass ForDefinition_t in places it is redundant.

I found this while looking at the ppc failures caused by the dso_local
change.

The issue was that the patch would produce the wrong answer for
available_externally. Having ForDefinition_t available in places where
the code can just check the linkage is a bit of a foot gun.

This patch removes the ForDefiniton_t argument in places where the
linkage is already know.

llvm-svn: 324499