[PATCH] Fix for PR18921.

[Stepan Dyatkovskiy]

  I see no NL at EOF in test/MC/ARM/ldrd-strd-gnu-arm-bad-imm.s. That will fixed in commit.
  Renato,
  non gnu ldrd/strd has tests already, so if, in you first inline comment you meant
  ldrd r0, r1, [r2, #123]
  Then it already tested in arm-ldrd.s, arm-memory-instructions.s, basic-thumb2-instructions.s.

  > negative tests

  Yes, we have ldrd-strd-gnu-thumb-bad-regs.s test for it.

http://llvm-reviews.chandlerc.com/D3277