Add --dry-run flag to run-libcore-tests.sh

Flag prints vogar command that would be invoked otherwise.

Test: art/tools/run-libcore-tests.sh --host --dry-run
Test: art/tools/run-libcore-tests.sh --host
Change-Id: Ie6dba8e8e12c0d3668ac430115c83373f7464720
1 file changed