test: lib: add initjmp() test

Test the initjmp() function when HAVE_INITJMP is set. Use the test as an
example in the API documentation.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
3 files changed