Add libwm to clean-light target      Now that the libwm target is no longer .PHONY, we need to clean it when cleaning lib/libfluidity.a (for example via clean-light).  This ensures that make; make clean-light; make works as a build sequence.
Add libwm to clean-light target
    
Now that the libwm target is no longer .PHONY, we need to clean it
when cleaning lib/libfluidity.a (for example via clean-light).  This
ensures that make; make clean-light; make works as a build sequence.

FluidityProject/multifluids,FluidityProject/multifluids,FluidityProject/multifluids,FluidityProject/multifluids