SVA: test for sequence concatenation with 0 delay

This extends an existing test with the case of a sequence concatenation
delay 0.

Author: kroening

regression/verilog/SVA/sequence4.sv

@@ -11,4 +11,6 @@ module main;
   // sequence concatenation
   initial p0: assert property (x == 0 ##1 x == 1 ##1 x == 2);
 
+  initial p1: assert property (x == 0 ##0 x == 0 ##1 x == 1);
+
 endmodule