Backend: Fix llvm40 assert about literal structs
Backend: Fix llvm40 assert about literal structs

In llvm literal structs have no name, so check it first.

Signed-off-by: Pan Xiuli <e5a665b1e626c5dc0826076a8b5a209eb48bf6ee@intel.com>
Reviewed-by: Guo, Yejun <1f883e24fa2949df61a83c432caa290810cece11@intel.com>

wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet