Use standard apt-xapian-index location, rather than libept

Part of the process to drop libept (see bug #677551):

  In src/generic/apt/matching/match.cc there's already
  #ifdefs to do everything via libxapian. The only ept-only
  bit is ept::axi::path_db(). That can be replaced with
  "/var/lib/apt-xapian-index/index", which is the standard
  index location which is NOT going to change (that's
  actually a xapian pointer to the real index location: try
  "cat /var/lib/apt-xapian-index/index").

Also add configure check for libxapian headers.

1 files changed, 2 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 9af97aa6..aaf1eab3 100644
--- a/NEWS
+++ b/NEWS
@@ -187,6 +187,8 @@ behaviour is desirable for two reasons:
     - repeat if package manager result is DoAgain;
     - report all download errors not just the first;
 
+  * Use standard apt-xapian-index location, rather than libept.
+
 - Cosmetic and UI bugs:
 
   * [cmdline]: Use arch-qualified names for virtual packages in