simlib: blackbox `$print` cell

It's possible to `generate` the appropriate always blocks per the
triggers, but unlikely to be worth parsing the RTLIL \FORMAT parameter.

techlibs/common/simlib.v

@@ -1799,6 +1799,23 @@ end
 
 endmodule
 
+// --------------------------------------------------------
+
+module \$print (EN, TRG, ARGS);
+
+parameter FORMAT = "";
+parameter ARGS_WIDTH = 0;
+parameter TRG_ENABLE = 1;
+
+parameter TRG_WIDTH = 0;
+parameter TRG_POLARITY = 0;
+
+input EN;
+input [TRG_WIDTH-1:0] TRG;
+input [ARGS_WIDTH-1:0] ARGS;
+
+endmodule
+
 // --------------------------------------------------------
 `ifndef SIMLIB_NOSR