Verilog: KNOWNBUG for primitive gates with more than two inputs

This replicates issue #880.

Author: kroening

regression/verilog/primitive_gates/or1.desc

@@ -0,0 +1,10 @@
+KNOWNBUG
+or1.sv
+--bound 0
+^EXIT=0$
+^SIGNAL=0$
+--
+^warning: ignoring
+--
+This is a small version of a misencoding of the Verilog primitive gates
+reported as https://github.com/diffblue/hw-cbmc/issues/880

regression/verilog/primitive_gates/or1.sv

@@ -0,0 +1,13 @@
+module main(input or_in1, or_in2, or_in3);
+
+  wire  or_out;
+
+  or o1(or_out, or_in1, or_in2, or_in3);
+
+  // should pass
+  or_ok: assert final ((or_in1 || or_in2 || or_in3)==or_out);
+
+  // should fail
+  or_not_ok: assert final (or_out == (or_in1 || or_in2));
+
+endmodule