test output: respect $TEST_OUTPUT_DIRECTORY

test output: respect $TEST_OUTPUT_DIRECTORY

Most test results go in $TEST_OUTPUT_DIRECTORY, but the output files for
tests run with --tee or --valgrind just use bare "test-results".
Changes these so that they do respect $TEST_OUTPUT_DIRECTORY.

As a result of this, the valgrind/analyze.sh script may no longer
inspect the correct files so it is also updated to respect
$TEST_OUTPUT_DIRECTORY by adding it to GIT-BUILD-OPTIONS.  This may be a
regression for people who have TEST_OUTPUT_DIRECTORY in their config.mak
but want to override it in the environment, but this change merely
brings it into line with GIT_TEST_OPTS which already cannot be
overridden if it is specified in config.mak.

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>