clast.c: don't insert any "scalars" for level 0
clast.c: don't insert any "scalars" for level 0

f8b6a419a532d644b2379bff78b62a75bfe74502 (Handle 0D problems by adding a
0th level to the main recursion) introduced a level 0 and was careful
not to generate any loops for this level, but we should also avoid
inserting "scalars" for this virtual level.

Signed-off-by: Sven Verdoolaege <e5350bbed4977f5eb8ae1dc6abd9ae59d21ace75@kotnet.org>

SaberMod/cloog-current,Distrotech/cloog,SaberMod/cloog-current,evaautomation/cloog,heysion/cloog-clone,VanirLLVM/toolchain_cloog,Distrotech/cloog,Syllo/cloog,cfx-next/toolchain_cloog-upstream,VanirLLVM/toolchain_cloog,UBERTC/cloog,epowers/cloog,cfx-next/toolchain_cloog-upstream,heysion/cloog-clone,Distrotech/cloog,epowers/cloog,Syllo/cloog,UBERTC/cloog,periscop/cloog,evaautomation/cloog,UBERTC/cloog,cfx-next/toolchain_cloog-upstream,VanirLLVM/toolchain_cloog,periscop/cloog,epowers/cloog,heysion/cloog-clone