SVN r345675 breaks kernel build with fuse

[Michael Butler]

As below .. an unused variable when KASSERT is not enabled ..

Building /usr/obj/usr/src/amd64.amd64/sys/TOSHI/fuse_ipc.o
--- fuse_ipc.o ---
/usr/src/sys/fs/fuse/fuse_ipc.c:223:22: error: unused variable 'ftick'
[-Werror,-Wunused-variable]
        struct fuse_ticket *ftick = mem;
                            ^
1 error generated.
*** [fuse_ipc.o] Error code 1

	imb