samba4: change perl dependency to fix menuconfig

Adding perlbase-json-pp to samba4-libs dependencies was the wrong approach and caused
samba packages not to be offered by menuconfig. AFAIK perlbase-json-pp is a perl helper
to building samba4 and seems to be already included in perl/host so use that instead to
fix the menuconfig issues.

Signed-off-by: Andrew Sim <andrewsimz@gmail.com>