Fix hanging barriers if number of parallel regions exceeds UINT_MAX

The fix is to make b_arrived flag 64 bit in both structures - kmp_balign_team_t
and kmp_balign_t. Otherwise when flag in kmp_balign_team_t wrapped over
UINT_MAX the library hangs.

Differential Revision: http://reviews.llvm.org/D12563

llvm-svn: 247320