Unit test runner ergonomics

- Catch and classify as INTERNAL_ERROR unix signals thrown by
  reference model
- Made -t a required argument

Change-Id: I2be1ed6f5c1e862d6a3aee43c6b1e8575ab50d1f
Signed-off-by: Jared Smolens <jared.smolens@arm.com>
diff --git a/verif/tosa_verif_run_ref.py b/verif/tosa_verif_run_ref.py
index 3f23f6b..0bfca0f 100755
--- a/verif/tosa_verif_run_ref.py
+++ b/verif/tosa_verif_run_ref.py
@@ -57,7 +57,13 @@
 
     parser = argparse.ArgumentParser()
     parser.add_argument(
-        "-t", "--test", dest="test", type=str, nargs="+", help="Test(s) to run"
+        "-t",
+        "--test",
+        dest="test",
+        type=str,
+        nargs="+",
+        help="Test(s) to run",
+        required=True,
     )
     parser.add_argument(
         "--seed",