for kernel testcases that using main() method to execute, when invoke
tst_exit() on execute finished, will report " executed from newlib!"
error, this is caused by two kinds kernel testcases are forbidded linked
together, in Linux this is OK, but for NuttX, this is necssary, so we
choose to modify the NO_NEWLIB_ASSERT macro's implementation, thus to
make kernel testcases can work in NuttX
Signed-off-by: guoshichao <guoshichao@xiaomi.com>