replicate-*-table rules which exclude 'mysql' tables
(e.g. replicate-wild-ignore-table=mysql.%).
This was already the behaviour for GRANT/REVOKE, I'm extending it to
SET PASSWORD because it seems very logical (the contrary seems illogical).
2 new tests:
- one to test if GRANT and SET PASSWORD are replicated
- one to test if they are not replicated if replicate-wild-ignore-table=mysql.%
The 2nd is also a testcase for BUG#980.


sql/sql_acl.cc:
  Fix so that SET PASSWORD is not replicated by the slave if running with
  replicate-*-table rules which exclude 'mysql' tables
  (e.g. replicate-wild-ignore-table=mysql.%).
  This was already the behaviour for GRANT/REVOKE, I'm extending it to
  SET PASSWORD because it seems very logical (the contrary seems illogical).