reject invalid comma stuff with a message. We reject the case in

reject invalid comma stuff with a message.  We reject the case in
PR6888 with:

$ llvm-as t.ll
llvm-as: t.ll:2:29: error: expected metadata or 'align'
 store <3 x i32> %x, i32 1, i32 1>, <3 x i32>* %p
                            ^

instead of:

$ llvm-as t.ll
llvm-as:

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102154 91177308-0d34-0410-b5e6-96231b3b80d8