Bug#178002: mklibs: Fail to handle .so files

[Petter Reinholdtsen <pere@hungry.com>]

I tested the slang frontend by hand, and discovered that slang.so
require libm.  Checking /usr/bin/mklibs I discovered this text:

  # HACK: exclude libm, since we don't need it for anything

I believe this hack must be removed to get the slang frontend working.