xprop: Test fixes and abort on test failure

Use `$finish(0)` to silently exit even when using recent iverlog
versions. Run `write_verilog -noexpr` before `write_verilog` as the
latter can modify the design.

This also enables checking the tests results, as xprop should be in a
state where the existing tests pass.

tests/xprop/generate.py

@@ -33,7 +33,7 @@ def add_test(name, src, seq=False):
     print(
         f"\t@cd {workdir} && python3 -u ../test.py -S {args.seed} -c {args.count}{seq_arg} > test.log 2>&1 || echo {workdir}: failed > status\n"
         f"\t@cat {workdir}/status\n"
-        # f"\t@grep '^.*: ok' {workdir}/status\n"
+        f"\t@grep '^.*: ok' {workdir}/status\n"
         ,
         file=makefile,
     )

tests/xprop/test.py

@@ -275,7 +275,7 @@ if "prepare" in steps:
                 file=tb_file,
             )
 
-        print("    $finish;", file=tb_file)
+        print("    $finish(0);", file=tb_file)
         print("end", file=tb_file)
         print("endmodule", file=tb_file)
 
@@ -344,8 +344,8 @@ for mode in ["", "_xprop"]:
                 read_rtlil wrapped{mode}.il
                 chformal -remove
                 dffunmap
-                write_verilog -noparallelcase vsim_expr{mode}.v
                 write_verilog -noexpr vsim_noexpr{mode}.v
+                write_verilog -noparallelcase vsim_expr{mode}.v
             """
         )