qa/new: small rework for --valgrind tests and support
qa/new: small rework for --valgrind tests and support

Set $do_valgrind rather than relying on $1 == "--valgrind" so we can
accommodate testing from shell procedures (like qa/1280).

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