[Cmake] Empty library names

[Amitha Perera]

I find that CMake uses empty library names when generating VS6 DSP
files. That is,
  LINK_LIBRARIES( ${MPEG_LIBRARIES} )
results in a link line with ".lib" when MPEG_LIBRARIES is "".

The Unix generator skips such libraries. I assume this is a bug, not a
feature. Is it possible to get this fixed in 1.4 beta (and therefore
in 1.4)? With the bug present, I'd have to write

  IF(HAS_MPEG)
    LINK_LIBRARIES( ${MPEG_LIBRARIES} )
  ENDIF(HAS_MPEG)

which is not as convenient, especially when there are a number of such
variables.

Thanks,
Amitha.