[GISel] Check useLoadStackGuardNode() before generating LOAD_STACK_GUARD

When lowering llvm::stackprotect intrinsic, the SDAG implementation
checks useLoadStackGuardNode() to either create a LOAD_STACK_GUARD or use
the first argument of the intrinsic. This check is not present in the
IRTranslator, which results in always generating a LOAD_STACK_GUARD even
if the target does not support it.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D129505