X86 codegen tweak to use lea in another case:

X86 codegen tweak to use lea in another case:

Suppose base == %eax and it has multiple uses, then instead of
  movl %eax, %ecx
  addl $8, %ecx
use
  leal 8(%eax), %ecx.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26323 91177308-0d34-0410-b5e6-96231b3b80d8