- redirect valgrind reports to a dedicated file rather than console
- try to avoid killing instances with SIGKILL so that we get the memory
leak report (killing with SIGTERM before resorting to SIGKILL)
- search for valgrind reports when done, print them and fail the tests
- add --dont-clean option to keep the logs on exit
- fix exit error code when crash is found (would have exited with 0)
changes that affect the normal redis test suite:
- refactor check_valgrind_errors into two functions one to search and
one to report
- move the search half into util.tcl to serve the cluster tests too
- ignore "address range perms" valgrind warnings which seem non relevant.