17045: sys/coding: add XOR based coding module r=benpicco a=benpicco
19243: cpu/gd32v: add periph_gpio_ll and periph_gpio_ll_irq support r=benpicco a=gschorcht
### Contribution description
This PR provides the `periph_gpio_ll` and `periph_gpio_ll_irq` support for GD32VF103. Level triggered interrupts are emulated.
`periph_gpio_ll_irq` could be split off from this PR as a separate PR if necessary.
### Testing procedure
Use any GD32V board and connect PA0 -> PB0 and PA1 -> PB1 where PA is the output port and PB the input port. With these connections `tests/periph_gpio_ll` should work.
```
BOARD=sipeed-longan-nano make -j8 -C tests/periph_gpio_ll flash term
```
If necessary, change the input and output pins by setting the environment variables and connect the corresponding pins, for example for `seeedstudio-gd32` PA1 -> PB8 and PA8 -> PB9:
```
PIN_OUT_0=1 PIN_OUT_1=8 PIN_IN_0=8 PIN_IN_1=9 BOARD=seedstudio-gd32 make -j8 -C tests/periph_gpio_ll flash term
```
### Issues/PRs references
Co-authored-by: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
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