unit: do not pass NULL to memcpy()

memcpy() should not receive NULL as source pointer and such is passed
from test_snep_read_get_req_frags_client_resp() and
test_snep_read_verify_resp().  ASAN reports:

    unit/test-snep-read.c:325:2: runtime error: null pointer passed as argument 2, which is declared to never be null
    unit/test-snep-read.c:266:2: runtime error: null pointer passed as argument 2, which is declared to never be null

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
1 file changed