[SCM] Samba Shared Repository - branch master updated

[tridge at samba.org]

 > Ok, it would be indeed easier if the build system could simply mkdir it
 > when needed rather then blow.

it could, and I originally did that, but it breaks the "no writes
outside of the build dir" rule, which matters when you try to make out
of tree builds work.

So I went for the simpler solution of having an empty directory in git
with a README file as a marker. Maybe I should have called it
README_DONT_DELETE :-)

Cheers, Tridge