libfuse: not available for static builds

Unfortunately libfuse uses dl functions exclusively so it can't be used
for static builds so exclude it so.
Fixes:
http://autobuild.buildroot.net/results/a1c3d2b9c436023675c363d9d3b365c95ade0329/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>