Fix sign extend to long. When coming from sbyte, we used to generate:

Fix sign extend to long.  When coming from sbyte, we used to generate:

        movsbl 4(%esp), %eax
        movl %eax, %edx
        sarl $7, %edx

Now we generate:

        movsbl 4(%esp), %eax
        movl %eax, %edx
        sarl $31, %edx

Which is right.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19515 91177308-0d34-0410-b5e6-96231b3b80d8