core: don't set the error number if zalloc() fails
core: don't set the error number if zalloc() fails

zalloc() is implemented locally and already sets the error number on
failure.

Signed-off-by: Bartosz Golaszewski <108de5fbc428215dc26df4468b48691526611148@gmail.com>

clemensg/libgpiod,brgl/libgpiod,brgl/libgpiod,brgl/libgpiod,brgl/libgpiod,clemensg/libgpiod