Xcode: Fix regression that automatically links libraries in source list

In commit e637744c (Xcode: Use "Link Binary With Libraries" to link
any library, 2019-07-10, v3.19.0-rc1~494^2~1) we accidentally added all
the library type files to "Link Binary With Libraries" build phase if
they were passed in as source files.  Revert that change as any actually
linked libraries will be added to that build phase later in the
`AddDependAndLinkInformation` call.

Fixes: #21361