If the CPSR is defined by a copy, then we don't want to merge it into an IT

block. E.g., if we have:

  movs  r1, r1
  rsb   r1, 0
  movs  r2, r2
  rsb   r2, 0

we don't want this to be converted to:

  movs  r1, r1
  movs  r2, r2
  itt   mi
  rsb   r1, 0
  rsb   r2, 0

PR11107 & <rdar://problem/10259534>

llvm-svn: 141589