string values from Go to C and back to Go.

Using //export in a file places a restriction on the preamble:
since it is copied into two different C output files, it must not
contain any definitions, only declarations. If a file contains both
definitions and declarations, then the two output files will produce
duplicate symbols and the linker will fail. To avoid this, definitions

// See the License for the specific language governing permissions and
// limitations under the License.

// Package clioptions contains flags which can be added to istioctl commands.