Fix bug 10025 - Lack of Sanity Checking in calls to malloc()/calloc().

Fix bug 10025 - Lack of Sanity Checking in calls to malloc()/calloc().

In reviewing various files in Samba-4.0.7, I found a number
of instances where malloc()/calloc() were called without the
checking the return value for a value of NULL, which would
indicate failure.

(NB. The changes needed to ccan, iniparser, popt and heimdal
will be reported upstream, not patched inside Samba).

Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Simo Source <idra@samba.org>