fix kernel launch check in cross kernel
Summary: per title
Test Plan: buck test mode/opt //caffe2/test:kernel_launch_checks -- --exact 'caffe2/test:kernel_launch_checks - test_check_cuda_launches (test_kernel_launch_checks.AlwaysCheckCudaLaunchTest)' --run-disabled
Reviewed By: r-barnes
Differential Revision: D29335739
fbshipit-source-id: 385c66b1806886deba35f7fd83e29e0885999119
