Turn sdiv into udiv if both operands have a clear sign bit. This occurs

Turn sdiv into udiv if both operands have a clear sign bit.  This occurs
a few times in crafty:

OLD:    %tmp.36 = div int %tmp.35, 8            ; <int> [#uses=1]
NEW:    %tmp.36 = div uint %tmp.35, 8           ; <uint> [#uses=0]
OLD:    %tmp.19 = div int %tmp.18, 8            ; <int> [#uses=1]
NEW:    %tmp.19 = div uint %tmp.18, 8           ; <uint> [#uses=0]
OLD:    %tmp.117 = div int %tmp.116, 8          ; <int> [#uses=1]
NEW:    %tmp.117 = div uint %tmp.116, 8         ; <uint> [#uses=0]
OLD:    %tmp.92 = div int %tmp.91, 8            ; <int> [#uses=1]
NEW:    %tmp.92 = div uint %tmp.91, 8           ; <uint> [#uses=0]

Which all turn into shrs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24190 91177308-0d34-0410-b5e6-96231b3b80d8