Hide some private macros from Doxygen.

* subversion/include/svn_config.h:
  (SVN_CONFIG__DEFAULT_GLOBAL_IGNORES_LINE_1,
   SVN_CONFIG__DEFAULT_GLOBAL_IGNORES_LINE_2): Hide from doxygen.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1512119 13f79535-47bb-0310-9956-ffa450edef68