JitArm64_Integer: cmpl - Subtract shifted 12-bit constant

You can encode a shifted 12-bit immediate in a SUB instruction on ARM64.
We exploit this to avoid materializing the immediate.

This approach saves an instruction if it does not need to be
materialized in a register afterwards. Otherwise, we just materialize
it later and the total number of instructions stays the same.

Before:
0x52a00218   mov    w24, #0x100000            ; =1048576
0xcb180379   sub    x25, x27, x24

After:
0xd1440379   sub    x25, x27, #0x100, lsl #12 ; =0x100000

Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp

@@ -736,6 +736,10 @@ void JitArm64::cmpl(UGeckoInstruction inst)
     else
       SUB(CR, EncodeRegTo64(gpr.R(a)), imm);
   }
+  else if (gpr.IsImm(b) && (gpr.GetImm(b) & 0xFFF000) == gpr.GetImm(b))
+  {
+    SUB(CR, EncodeRegTo64(gpr.R(a)), gpr.GetImm(b) >> 12, true);
+  }
   else
   {
     SUB(CR, EncodeRegTo64(gpr.R(a)), EncodeRegTo64(gpr.R(b)));