Revert "BUG Make sure bin/cython imports the right Cython module"

This reverts commit af902b50.

As I was told: Please remember that 'bin/cython' is the script that
gets installed in '/usr/bin'. Why should '/usr' git injected in
sys.path?

bin/cygdb

 #!/usr/bin/env python
 
 import sys
-import os
-
-# Make sure we import the right Cython
-binpath, _ = os.path.split(os.path.realpath(__file__))
-cythonpath, _ = os.path.split(binpath)
-sys.path.insert(0, cythonpath)
 
 from Cython.Debugger import Cygdb as cygdb
 

bin/cython

@@ -4,13 +4,5 @@
 #   Cython -- Main Program, Unix
 #
 
-import os
-import sys
-
-# Make sure we import the right Cython
-binpath, _ = os.path.split(os.path.realpath(__file__))
-cythonpath, _ = os.path.split(binpath)
-sys.path.insert(0, cythonpath)
-
 from Cython.Compiler.Main import main
 main(command_line = 1)