drd/tests/atomic_var: Revert r13876.

r13876 was a workaround for false ordering introduced by platform-specific
(Solaris) code. The conclusion of an off-list discussion was that this has
to be solved in the drd tool itself and not by modifying test programs. Hence
this revert.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13980 a5019735-40e9-0310-863c-91ae7b9d1cf9