Ability to set the results.txt filename and paths and ignore other, and empty/non existent file if no error are found

hi,

First thanks a lot to all developers involved in this projects (and related). Amazing tools and finally something usable for Windows.

I am adding drmemory support for the php test suite (which uses valgrind only and only on linux). We have a couple of 1000s tests, dispatched across the src tree with a relatively clear naming convention.

What we do using valgrind is to use the logfile option:
valgrind -q --tool=memcheck --trace-children=yes --log-file=$memcheck_filename $cmd

$cmd being the php cmd with all necessary options.

It makes things slightly more complicated and slow when using DrMemory as the script have to walk through the directory structure of the logdir options. The exit code on error option helps a bit as we at least do not have to parse the file to figure it out.

Would it be possible to have a similar option for DrMemory? -resultfile tests/foo/testname.mem for example will store the results.txt in tests/foo/testname.mem. It would be also nice to simply ask not to store anything else, maybe using -nolog or something like that, or disable other logs when resultfile is used.

I can work a PR if you agree on this feature.

Some ref:
valgrind call in our tests script:
https://github.com/php/php-src/blob/master/run-tests.php#L1845

Thanks!