qa/common.check: support _run_valgrind --sudo
qa/common.check: support _run_valgrind --sudo

Needed by qa/1188 to run valgrind as root. Uses similar mechanism
as __run_helgrind --sudo ...
modified:   qa/common.check

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp