tests: Add .exp files for basics/parser and import/import_override.

Because CPython 3.8.0 now produces different output:
- basics/parser.py: CPython does not allow '\\\n' as input.
- import/import_override: CPython imports _io.

tests/basics/parser.py.exp

@@ -0,0 +1,3 @@
+SyntaxError
+SyntaxError
+SyntaxError

tests/import/import_override.py.exp

@@ -0,0 +1,2 @@
+import import1b None 0
+456