Fixes issue with preexec scripts creating a share directory, and problems if a smb...

Fixes issue with preexec scripts creating a share directory, and problems if a smb.conf reload turns wide links back on after a connection is establised.

Includes git refs :
cd18695fc2e4d09ab75e9eab2f0c43dcc15adf0b
94865e4dbd3d721c9855aada8c55e02be8b3881e
5d92d969dda450cc3564dd2265d2b042d832c542
02a5078f1fe6285e4a0b6ad95a3aea1c5bb3e8cf
a6f402ad87ff0ae14d57d97278d67d0ceaaa1d82

from master.

Jeremy.

Fix bug #7104 ("wide links" and "unix extensions" are incompatible.)
(cherry picked from commit ce04bf60499104c166657df959e4033573b5be5c)