Committed with a typo-fix in the text, /an list/a list/, and in the change log /details about implementation/details about the implementation/.
2015-04-14 Matthew Wahab <matthew.wa...@arm.com> * doc/extend.texi (__sync Builtins): Simplify some text. Update details about the implementation. Make clear preference for __atomic builtins. Reduce possibility of future change. Matthew