Add regression test for br_gh672.

ivtest/ivltests/br_gh672.v

@@ -0,0 +1,28 @@
+module top;
+
+    logic clk = 0;
+    int cnt = 0;
+
+    always @(posedge clk) begin
+        fork begin
+            #(10*2); // Wait 10 clock periods
+            cnt++;
+        end
+        join_none
+    end
+
+    initial begin
+        $display("Starting test");
+        repeat (100) begin
+            #1 clk = 1;
+            #1 clk = 0;
+        end
+        #(10*2); // Wait 10 clock periods
+        $display("cnt = %0d", cnt);
+        if (cnt === 100)
+            $display("PASSED");
+        else
+            $display("FAILED");
+        $finish(0);
+    end
+endmodule

ivtest/regress-sv.list

@@ -209,6 +209,7 @@ br_gh556		normal,-g2009		ivltests
 br_gh568		normal,-g2009		ivltests
 br_gh661a		normal,-g2009		ivltests
 br_gh661b		normal,-g2009		ivltests
+br_gh672		normal,-g2009		ivltests
 br_ml20171017		normal,-g2009		ivltests
 br_ml20180227		CE,-g2009		ivltests
 br_ml20180309a		normal,-g2009		ivltests

ivtest/regress-vlog95.list

@@ -431,6 +431,7 @@ br_gh368		CE,-g2009		ivltests  # join_*
 br_gh412		CE,-g2009		ivltests  # queues
 br_gh414		CE,-g2009,-pallowsigned=1	ivltests  # strings
 br_gh436		CE,-g2012,-pallowsigned=1	ivltests  # queues/strings
+br_gh672		CE,-g2009		ivltests  # join_none
 br_mw20200501		CE,-g2009		ivltests  # queues
 disable_fork_cmd	CE,-g2009		ivltests  # disable fork and join_*
 enum_next		CE,-g2009,-pallowsigned=1	ivltests  # enum