There was no way to see if report-{host,port,user,password} were set up.

Fixed with introducing new global variables.
The variables are made read-only because of a possible need to change them
most probably require the slave server restart.

Todo: transform the startup options to be CHANGE master parameters - i.e
to deprecate `report-' options, and to change the new vars 
to be updatable at time of CHANGE master executes with new
values.


sql/set_var.cc:
  Adding associations of the server init arguments with the new global read-only
  variables.
mysql-test/suite/rpl/r/rpl_report.result:
  new results file
mysql-test/suite/rpl/t/rpl_report-slave.opt:
  options initialize the new global variables.
mysql-test/suite/rpl/t/rpl_report.test:
  The new test to check SHOW-ability and SELECT-ablity for the report
  global vars.