* include/bits/atomic_base.h (__atomic_flag_base): Define _M_i
based on the value of __GCC_ATOMIC_TEST_AND_SET_TRUEVAL.
(ATOMIC_FLAG_INIT): Initialize with 0, not false.
(atomic_flag::atomic_flag): Use __GCC_ATOMIC_TEST_AND_SET_TRUEVAL.
From-SVN: r183582