meson: Allow to set dlopen option for compression libraries

meson: Allow to set dlopen option for compression libraries

Add a dlopen option that allows toggling what libraries libkmod should
attempt to dlopen. If -Ddlopen=foo is passed, it means that library is
required to build, regardless of -Dfoo=*. However that library will
only be linked in if it's not set as dlopen.

Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
[ with disagreement on the need to toggle each one individually,
  it'd be better to be all-or-nothing dlopen'ed ]
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/262