Initialize memory correctly with C99 initializer (-Wmissing-field-initializers)

Hi,

this patchset should allow to build Samba with -Wmissing-field-initializers. However the compiler on Ubuntu 14.04 really sucks, not only in this regards. It complains about totally valid C99 initializer. That's the reason why -Wmissing-field-initializers is not enabled. I don't want to rewrite correct code.

However this patchset can be reviewed and pushed. It can also be done in smaller parts. Metze is still working to update sn-devel to 18.04 which would give us hopefully a sane compiler. I dunno what Ubuntu patched in 14.04.