testcase checks are made.
      
MTR spawns mysqltest to run check-testcase test before and after each testcase 
it runs. It can also run check-warnings using mysqltest. Since it happened on PB 
that these checks hanged, this patch provides additional feedback to help 
investigating such failures:
      
- mysqltest is modified to give feedback about main steps in execution of a 
testcase if run in verbose mode (including connection to the server),
     
- MTR is modified to run mysqltest in verbose mode when doing check-testcase or 
check-warnings. The diagnostic output from mysqltest is preserved so that it is 
saved upon test failure.

client/mysqltest.cc:
  Add verbose messages informing about main steps in execution of a testcase.
mysql-test/mysql-test-run.pl:
  - When doing check-testcase or check-warnings run mysqltest in verbose mode.
  - Do not delete the mysqltest's error log if errors are detected during these