[xctest_checker] Remove installation script

This Python module is only ever used by the XCTest functional tests, it
doesn't need a Python package installation script.

I initially added this installation script because I mistakenly thought
I needed it to run xctest_checker's tests. In fact they can be run like
so:

```
$ python -m unittest discover -s Tests/Functional/xctest_checker
```

Author: modocache

Tests/Functional/xctest_checker/setup.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-import xctest_checker
+import xctest_checker.main
 
 if __name__ == '__main__':
-    xctest_checker.main()
+    xctest_checker.main.main()

Tests/Functional/xctest_checker/xctest_checker.py

@@ -1,9 +0,0 @@
-from __future__ import absolute_import
-from .main import main
-
-__author__ = 'Brian Gesiak'
-__email__ = '[email protected]'
-__versioninfo__ = (0, 1, 0)
-__version__ = '.'.join(str(v) for v in __versioninfo__)
-
-__all__ = []