MDEV-7179: rpl.rpl_gtid_crash failed in buildbot with Warning: database page corruption or a failed

I saw two test failures in rpl.rpl_gtid_crash where we get this in the error
log:

141123 12:47:54 [Note] InnoDB: Restoring possible half-written data pages 
141123 12:47:54 [Note] InnoDB: from the doublewrite buffer...
InnoDB: Warning: database page corruption or a failed
InnoDB: file read of space 6 page 3.
InnoDB: Trying to recover it from the doublewrite buffer.
141123 12:47:54 [Note] InnoDB: Recovered the page from the doublewrite buffer.

This test case deliberately crashes the server, and if this crash happens
right in the middle of writing a buffer pool page to disk, it is not
unexpected that we can get a half-written page. The page is recovered
correctly from the doublewrite buffer.

So this patch adds a suppression for this warning in the error log for this
test case.

mysql-test/suite/rpl/r/rpl_gtid_crash.result

@@ -3,6 +3,7 @@ include/rpl_init.inc [topology=1->2]
 call mtr.add_suppression("Checking table:");
 call mtr.add_suppression("client is using or hasn't closed the table properly");
 call mtr.add_suppression("Table .* is marked as crashed and should be repaired");
+call mtr.add_suppression("InnoDB: Warning: database page corruption or a failed");
 flush tables;
 ALTER TABLE mysql.gtid_slave_pos ENGINE=InnoDB;
 CREATE TABLE t1 (a INT PRIMARY KEY, b INT) ENGINE=InnoDB;

mysql-test/suite/rpl/t/rpl_gtid_crash.test

@@ -12,6 +12,11 @@
 call mtr.add_suppression("Checking table:");
 call mtr.add_suppression("client is using or hasn't closed the table properly");
 call mtr.add_suppression("Table .* is marked as crashed and should be repaired");
+# We have seen this warning a couple of times in Buildbot. Since we crash the
+# server deliberately, it seems possible that we could in rare cases crash in
+# the middle of a page write. The page is recovered from the doublewrite
+# buffer ("[Note] InnoDB: Recovered the page from the doublewrite buffer.").
+call mtr.add_suppression("InnoDB: Warning: database page corruption or a failed");
 flush tables;
 
 ALTER TABLE mysql.gtid_slave_pos ENGINE=InnoDB;