core/macros: rewrite DIV_ROUND add DIV_ROUND_UINT

[kfessel]

with #18853 i had hope to remove SIGNOF from DIV_ROUND but tests showed that types and negative numbers had some false results, so this makes DIV_ROUND deliver what it promisses (math rounded division for integers that don't reach to high into the rage)

There are some variants to implement such thing at https://godbolt.org/z/TsKcnPoYx sadly most of them either fail in a specific range or if divisor or dividend is negative or unsigned are typical, so i choose the one that worked across the test range (DIV_ROUNDb) please feel free to find a better one.

Condition:
Working for either i or j or both being uint and for negative an positive values of i and j

Contribution description

This DIV_ROUND works for:

• either a or b or both being uint and
• for negative an positive values of a and b as expected

current upstream tells me -15 / -5 = rounded to nearest is 2 (that is wrong)
with this PR i get 3 (see the godbolt)

Oh and i shall not forget i added DIV_ROUND_UINT for the most likely usecases

this also circumvents the -Wtype-limits warning by having the same result for positive and 0 but 2 checks (thatat ar optimized away) an alternative would be to have 3 result 1,0,-1 or

#if defined(__GNUC__)
_Pragma("GCC diagnostic ignored \"-Wtype-limits\"")
#endif

Testing procedure

read, run tests, look at that linked compiler explorer

Issues/PRs references

this fixes the issue of #18849

#18853 was my first atempt on this

https://godbolt.org/z/TsKcnPoYx

[riot-ci]

Murdock results

✔️ PASSED

23bcc18 core/macros: rewrite DIV_ROUND add DIV_ROUND_UINT

Success	Failures	Total	Runtime
1999	0	2000	06m:27s

Artifacts

• Documentation preview

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[kfessel]

#18858 is better