mtr changes:

* expanding unknown env variable does not abort mtr
* have_archive, blackhole, innodb - preload the corresponding engine
* all options from .opt files get equal treatment, all are searched for special options,
  not only -{master,slave}.opt as before (which ignored suite.opt and --mysqld=...)
* --plugin-load gets special treatment too - all instances are merged into one
* federated test fixed to preload federated

mysql-test/include/have_archive.inc

@@ -1,4 +1,5 @@
---disable_query_log
---require r/true.require
-select (support = 'YES' or support = 'DEFAULT') as `TRUE` from information_schema.engines where engine = 'archive';
---enable_query_log
+if (!`SELECT count(*) FROM information_schema.engines WHERE
+      (support = 'YES' OR support = 'DEFAULT') AND
+      engine = 'archive'`){
+  skip Need archive engine;
+}

mysql-test/include/have_archive.opt

@@ -0,0 +1,2 @@
+--loose-archive
+--plugin-load=$HA_ARCHIVE_SO

mysql-test/include/have_blackhole.opt

@@ -0,0 +1,2 @@
+--loose-blackhole
+--plugin-load=$HA_BLACKHOLE_SO

mysql-test/include/have_innodb.opt

@@ -1 +1,2 @@
 --loose-innodb
+--plugin-load=$HA_XTRADB_SO

mysql-test/include/have_pbxt.inc

@@ -1,4 +1,5 @@
-disable_query_log;
---require r/true.require
-select (support = 'YES' or support = 'DEFAULT') as `TRUE` from information_schema.engines where engine = 'pbxt';
-enable_query_log;
+if (!`SELECT count(*) FROM information_schema.engines WHERE
+      (support = 'YES' OR support = 'DEFAULT') AND
+      engine = 'pbxt'`){
+  skip Need PBXT engine;
+}