Allow disabling the named test directory for cc_test

Some external test suites (LTP in this case), have their own expected
layout, and don't fit well with our
/data/nativetest/<testname>/<testname> layout, nor do they work with
test_per_src.

So allow setting no_named_install_directory along with
relative_module_path to specify a custom test path:

  no_named_install_directory: true,
  relative_module_path: "ltp/testcases/bin",

Test: Convert LTP
Change-Id: Ib002c058674e8b960a4fdc3af1a25c8bcaeb1d63