sv: fix always_comb auto nosync for nested and function blocks

tests/verilog/always_comb_nolatch_5.ys

@@ -0,0 +1,15 @@
+read_verilog -sv <<EOF
+module top;
+logic [4:0] x;
+logic z;
+assign z = 1'b1;
+always_comb begin : foo
+    x = '0;
+    if (z) begin : bar
+        for (int i = 0; i < 5; i++)
+            x[i] = 1'b1;
+    end
+end
+endmodule
+EOF
+proc