Remove redundant add_user_stats() and add_thread_stats().
Fix bug 1244110 (Top-level make fails in UDF autoreconf with Automake
1.13) by adding a conditional AM_PROG_AR call to UDF/configure.ac as
it's done in 5.5+.
Fix http://bugs.mysql.com/bug.php?id=68909 / bug 1244154 (In
my_MD5Final in mysys/md5.c, ctx is not properly zeroed as intended) by
backporting its fix from 5.5.
Fix http://bugs.mysql.com/bug.php?id=69407 / bug 1186190 (Build
warnings with mysql) by backporting the fix from 5.5.
Automerge lp:~sergei.glushchenko/percona-server/5.1-BT34411-ps-bug1082333
Automerge lp:~laurynas-biveinis/percona-server/ubuntu-13.10-5.1