Add ld version-script

Add ld version-script

Explicit symbol versioning allows us to provide multiple versions of
incompatible API changes. It is a very common practice in GNU world and
avoids the problems occuring if distributions try to ship multiple version
of a single DSO.

Background information available at:
  http://people.redhat.com/drepper/dsohowto.pdf

To see the symbol-versions, use objdump:
  objdump -T libevdev/.libs/libevdev.so.1.0.0
This can also be used to verify that all symbols are correctly
exported (typos in linker-scripts are silently ignored by ld).

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Updated for evdev 0.6's API.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>