[cuda] Ignore "TLS unsupported by target" errors for host variables during device compilation.

During device-side CUDA compilation clang currently complains about
all TLS variables, regardless of whether they are __host__ or
__device__.

This patch suppresses "TLS unsupported" errors for host variables
during device compilation and for device variables during host
compilation.

Differential Revision: http://reviews.llvm.org/D9269

llvm-svn: 235907