Add support for gtest options to `tools/run-gtests.sh`.

Have `tools/run-gtests.sh` accept gtest options after `--` on the
command line, and pass them verbatim to each executed gtest
binary.

Also document the use of gtest options with `tools/run-gtests.sh`
in `test/README.chroot.md`.

Test: art/tools/run-gtests.sh -- --gtest_list_tests
Test: art/tools/run-gtests.sh \
        /apex/com.android.art/bin/art/arm64/art_cmdline_tests \
        -- --gtest_list_tests
Test: Render `README.chroot.md` as HTML and check the output manually
Bug: 34729697
Change-Id: If41181666eb52750444b1b40dfab0629f802b7b5
2 files changed