First step towards V9 instructions in the V8 backend, two conditional move

First step towards V9 instructions in the V8 backend, two conditional move
patterns.  This allows emission of this code:

t1:
        save -96, %o6, %o6
        subcc %i0, %i1, %l0
        move %icc, %i0, %i2
        or %g0, %i2, %i0
        restore %g0, %g0, %g0
        retl
        nop

instead of this:

t1:
        save -96, %o6, %o6
        subcc %i0, %i1, %l0
        be .LBBt1_2     !
        nop
.LBBt1_1:       !
        or %g0, %i2, %i0
.LBBt1_2:       !
        restore %g0, %g0, %g0
        retl
        nop

for this:

int %t1(int %a, int %b, int %c) {
        %tmp.2 = seteq int %a, %b
        %tmp3 = select bool %tmp.2, int %a, int %c
        ret int %tmp3
}

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25809 91177308-0d34-0410-b5e6-96231b3b80d8