Add ROI base file that adds a clock divider.

This cannot be used for an ROI harness until
https://github.com/SymbiFlow/prjxray/issues/891 is complete.

Command to build new harness
```
XRAY_ROIV=../roi_base_div2.v make
```

Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>

minitests/roi_harness/roi_base_div2.v

@@ -0,0 +1,65 @@
+//See README and tcl for more info
+
+`include "defines.v"
+
+module roi(input clk,
+        input [DIN_N-1:0] din, output [DOUT_N-1:0] dout);
+    parameter DIN_N = `DIN_N;
+    parameter DOUT_N = `DOUT_N;
+
+    wire div_clk;
+    wire clk_IBUF_BUFG;
+    BUFR #(
+        .BUFR_DIVIDE(2)
+    ) clock_divider (
+        .I(clk),
+        .O(div_clk),
+        .CE(1),
+        .CLR(0)
+    );
+
+    BUFG clock_buffer (
+        .I(div_clk),
+        .O(clk_IBUF_BUFG)
+    );
+
+    genvar i;
+    generate
+        //CLK
+        (* KEEP, DONT_TOUCH *)
+        reg clk_reg;
+        always @(posedge clk_IBUF_BUFG) begin
+            clk_reg <= clk_reg;
+        end
+
+        //DIN
+        for (i = 0; i < DIN_N; i = i+1) begin:ins
+            (* KEEP, DONT_TOUCH *)
+            LUT6 #(
+                .INIT(64'b01)
+            ) lut (
+                .I0(din[i]),
+                .I1(1'b0),
+                .I2(1'b0),
+                .I3(1'b0),
+                .I4(1'b0),
+                .I5(1'b0),
+                .O());
+        end
+
+        //DOUT
+        for (i = 0; i < DOUT_N; i = i+1) begin:outs
+            (* KEEP, DONT_TOUCH *)
+            LUT6 #(
+                .INIT(64'b01)
+            ) lut (
+                .I0(1'b0),
+                .I1(1'b0),
+                .I2(1'b0),
+                .I3(1'b0),
+                .I4(1'b0),
+                .I5(1'b0),
+                .O(dout[i]));
+        end
+    endgenerate
+endmodule