Test LB+CSEL4

AArch64 LB+CSEL4
{
0:X1=x; 1:X1=x;
0:X3=y; 1:X3=y;
}
P0           | P1              ;
LDR W0,[X3]  | LDR W0,[X1]     ;
MOV W2,#1    | CMP W0,#0       ;
STLR W2,[X1] | CSEL W0,W0,W0,EQ;
             | MOV W4,#1       ;
             | STR W4,[X3]     ;
Observed
    1:X0=1; 0:X0=1;