examples/ad9361-iiostream: Fix assert() usage with NDEBUG
examples/ad9361-iiostream: Fix assert() usage with NDEBUG

Make sure we always evaluate the expression even when NDEBUG is defined.

Signed-off-by: Michael Hennerich <38f18d03059a1bc88082b55d7ca2d9b1ebfaffe0@analog.com>

analogdevicesinc/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio