Another set of fixes for returning -1 as bool

[Jeremy Allison]

On Sat, May 18, 2019 at 07:40:09AM +0200, Rikard Falkeborn via samba-technical wrote:
> Returning -1 from a function with bool as return value type is usually not
> correct. This follows up on commit 749f1290ce6 (
> https://lists.samba.org/archive/samba-technical/2019-May/133542.html) and
> fixes the remaining issues of this kind spotted by cppcheck.
> 
> I'm pretty sure about the first three patches. The last one basically
> inverts the return values of the test (except in one error path), which
> means either it has never worked as intended, or I have really
> misunderstood tthings completely.

Pushed to master, thanks !