Export macro_XXX_DEV macros (I2C_DEV)

[chrysn]

This makes a build time assertion on the signature being (on the C side) compatible with a single unsigned value. For many types that's a property documented in C tests; for the others, it's conjecture that is aligned with their general perception.

Contributes-To: RIOT-OS/rust-riot-wrappers#37

[chrysn]

In addition to the CI tests, I'm also running a full buildtest (currently at k) on the rust_minimal test, with these extra lines:

FEATURES_OPTIONAL += periph_i2c
FEATURES_OPTIONAL += periph_spi
FEATURES_OPTIONAL += periph_pwm
FEATURES_OPTIONAL += periph_uart
FEATURES_OPTIONAL += periph_gpio
FEATURES_OPTIONAL += periph_adc
FEATURES_OPTIONAL += periph_timer
FEATURES_OPTIONAL += periph_qdec

(Otherwise, the relevant functions would not be built for lack of macro definitions.)

Before doing the bors test when merging the PR that'll pull this in to main RIOT, it may make sense to add a similar alteration there, just to make sure the tests actually cover relevant parts.

[chrysn]

... and it's failing on samd10-xmini, investigating...

[chrysn]

... which it also does without the changes of this commit, so let's see how the larger build test goes.

The concrete error I got is:

"make" -C /home/chrysn/git/RIOT/sys/picolibc_syscalls_default
/home/chrysn/git/RIOT/sys/picolibc_syscalls_default/syscalls.c:319:1: error: unknown type name '_READ_WRITE_RETURN_TYPE'
  319 | _READ_WRITE_RETURN_TYPE read(int fd, void *dest, size_t count)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/home/chrysn/git/RIOT/sys/picolibc_syscalls_default/syscalls.c:351:1: error: unknown type name '_READ_WRITE_RETURN_TYPE'
  351 | _READ_WRITE_RETURN_TYPE write(int fd, const void *src, size_t count)
      | ^~~~~~~~~~~~~~~~~~~~~~~

which has the suspicious "picolibc" in there. Nothing wrong with picolibc probably, but it could be triggering some rarer code paths. I'll try not to lose track of it, but this is several layers of yak fur in.

[chrysn]

OK, full boards survey:

• samd10-xmini, nucleo-l011k4 and stm32f030f4-demo: same picolibc issue.
• The riscv boards generally fail on my host, but built fine in Docker when using this branch and the modified rust_minimal test.

As this PR would only break things build time, that's all I can test.