[Samba] my patch to tdb - no spinlock version

[Chere Zhou]

Hello,  I want to make a change and need to know if it makes sense. I don't 
use spinlocks.  So in tdb_clear_spinlocks(), it writes rwlocks=0 back to the 
files, which is called in tdb_open_ex. I want to change it to write rwlocks=0 
in the call to tdb_new_database().  Then you will only write it once when you 
create the file, instead of every time open the file with write access.  This 
is for 2.2.5. 

Does my change break anything?

Chere