Update runtests.py: add selfc

Author: wyattscarpenter

runtests.py

@@ -65,6 +65,17 @@
         "-p",
         "mypyc",
     ],
+    # Self type check, but use mypyc;
+    # for instance, to catch nasty mypyc bugs.
+    "selfc": [
+        "mypyc",
+        "--config-file",
+        "mypy_self_check.ini",
+        "-p",
+        "mypy",
+        "-p",
+        "mypyc",
+    ],
     # Type check setup.py as well
     "self-packaging": [
         executable,