Unbreak 'make clean-ctypes-python'.

* Makefile.in
  (CTYPES_BUILD_OUTPUTS): Remove.
  (clean-ctypes-python): Hardcode its value.  This fixes some quoting issues.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1479329 13f79535-47bb-0310-9956-ffa450edef68