configure: Do not create/install versioned DLLs on OS/2.

Only one DLL for each module must be present on OS/2: SLIBNAME_WITH_MAJOR
(the same as on Windows). Creating other DLLs makes no sense as they can't
be used.

Signed-off-by: Dave Yeo <daveryeo@telus.net>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>