ARM64: Use the shifter operands.

This introduces architecture-specific instruction simplification.
On ARM64 we try to merge shifts and sign-extension operations into
arithmetic and logical instructions.

For example for the Java code

    int res = a + (b << 5);

we would generate

    lsl w3, w2, #5
    add w0, w1, w3

and we now generate

    add w0, w1, w2, lsl #5

Change-Id: Ic03bdff44a1c12e21ddff1b0513bd32a730742b7