* tests which use MERGE or INSERT DELAYED should run only

with engines which support that
* temporarily adding option --global-subst to mysqltest so that
the full testsuite can be run using Maria tables without failing
on trivial differences (like diff in the engine clause of
SHOW CREATE TABLE)
* using recognizable tags for todos of the Maria team


client/mysqltest.c:
  temporarily adding option --global-subst: its argument is X,Y.
  It replaces all occurrences of X by Y into mysqltest's result
  before the comparison with the expected result is done.
  This serves for when a test is run with --default-storage-engine=X
  where X is not MyISAM: tests using SHOW CREATE TABLE will always fail
  because SHOW CREATE TABLE prints X instead of MyISAM. With
  --global-subst=X,MyISAM , such trivial differences are eliminated and
  test may be reported as passing.
  For example, --global-subst=MARIA,MyISAM
  This is not good enough for merging into main trees! just for running
  many tests and finding bugs now!
mysql-test/mysql-test-run.pl:
  new option --mysqltest to pass options to mysqltest (like we have
  --mysqld). Used for example like this:
  ./mtr --mysqltest=--global-subst=MARIA,MyISAM
mysql-test/r/merge.result:
  update
mysql-test/t/delayed.test:
  run test only with engines which support INSERT DELAYED
mysql-test/t/merge.test:
  run test only with MyISAM tables, as they are required by MERGE
sql/sql_delete.cc:
  recognizable tag
sql/table.cc:
  recognizable tag
storage/maria/ha_maria.cc:
  recognizable tag
storage/maria/ma_check.c:
  recognizable tag
storage/maria/ma_create.c:
  recognizable tag

mysql-test/t/delayed.test

@@ -5,6 +5,15 @@
 # (Can't be tested with purify :( )
 #
 
+# limit the test to engines which support INSERT DELAYED
+disable_query_log;
+--require r/true.require
+select @@global.storage_engine in
+("memory","myisam","archive","blackhole") and
+@@session.storage_engine in
+("memory","myisam","archive","blackhole") as `TRUE`;
+enable_query_log;
+
 --disable_warnings
 drop table if exists t1;
 --enable_warnings