Update version in mysql-next-mr.

According to new numbering scheme mysql-next-mr does not have
its own version. Some version placeholder is used instead.

It's been agreed that 5.5.99 will be used as a placeholder.

.bzr-mysql/default.conf

 [MYSQL]
 post_commit_to = "commits@lists.mysql.com"
 post_push_to = "commits@lists.mysql.com"
-tree_name = "mysql-5.6-next-mr"
+tree_name = "mysql-5.5-next-mr"

configure.in

@@ -25,7 +25,7 @@ AC_CANONICAL_SYSTEM
 #
 # When changing major version number please also check switch statement
 # in client/mysqlbinlog.cc:check_master_version().
-AM_INIT_AUTOMAKE(mysql, 5.6.0-beta)
+AM_INIT_AUTOMAKE(mysql, 5.5.99)
 AM_CONFIG_HEADER([include/config.h:config.h.in])
 
 # Request support for automake silent-rules if available.