4947316122
1) Cannot assume that blockIdx.x = 0 and threadIdx.x = 0 will be
run first in TestKernel. Initialize flags outside kernels.
2) use __hip_atomic_store in device code and __atomic_store_n for host.
Change-Id: If4e9274d2c16af55b53a626c3ba2fb0db7052d4b
[ROCm/hip-tests commit: fc270bc90c]