Do not use .xword and friends to emit zeros on V9. Apparently there are issues

Do not use .xword and friends to emit zeros on V9.  Apparently there are issues
with emitting .xwords when not on an 8-byte boundary (.xword 0 is not the
same as 8 .byte 0's).  Because we do not know when or when we are not aligned,
just emit bytes like the old V9 asmprinter did.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16006 91177308-0d34-0410-b5e6-96231b3b80d8