I am not understanding the point of using .def files with DLLs.
It seems that it replaces the need to use explicit exports within your DLL code (ie. explicit __decls
For those interested still... to be able to link to the dll and def file you also require a lib file. In windows this can be made from the def using the 'LIB' tool. See below for an example of the command line way of doing this.
lib /machine:i386 /def:sqlite3.def
Hope this helps others.