add support for C++11 atomic types instead of TBB

[slayoo]

As suggested by Patrik Jonsson on the mailing list: https://sourceforge.net/p/blitz/mailman/message/33068240/

It would be nice to add support for C++11 atomic types instead of TBB...

context:

you can make blitz use atomic data types instead of mutexes for the reference count by configuring it to use TBB

[slayoo]

this was migrated from SF: https://sourceforge.net/p/blitz/feature-requests/6/