- Adjust timing in test case, to avoid test failures caused by high load
   on machines and consequent race conditions in the test case.

 - Add another variant of Valgrind suppressions for memory leak in system
   libraries when unloading dynamic object files.


mysql-test/r/information_schema.result:
  Adjust timing to avoid test failures due to races.
mysql-test/t/information_schema.test:
  Adjust timing to avoid test failures due to races.
mysql-test/valgrind.supp:
  Add another variant of valgrind suppression for leak in system libs.