extern variable question

[Robert Reif]

I'm trying to write a Direct Input regression test and I ran into a
problem I can't resolve (and the linker too).  dinput.h defines an
extern variable:

extern const DIDATAFORMAT c_dfDIJoystick;

I can't find this variable in dinput.dll but it is in dinput.lib on
windows.  It looks like I need to generate a dinput.a.  How
can I generate both a dinput.dll.so and a dinput.a from the
same source?