Tightening symbol exports

> As there specifically is no stable API to outside drivers you do not have
> to think about breaking stuff outside the kernel anyway.

I think most people would consider a symbol involved in EXPORT_SYMBOL to be "somewhat stable",
i.e., yes it breaks from time to time, but nobody would expect it to break every minor kernel
version.  Also, such a mechanism would save developer from having to search in the whole
kernel source tree after making whatever minor change to function prototypes.

> The whole issue of using EXPORT_SYMBOL to limiting access is wrong. It was
> probably made to avoid exporting everything for mere technical reasons
> (limiting memory).

I don't think this is a case for any technical reason: after all, kernel modules can easily be
loaded with user-mode helpers which will resolve all the symbols needed, and the symbol
information is easily made available if not already available via the System.map.