This is meant as a substitute for sys_clock_timeout_end_calc()
Current sys_clock_timeout_end_calc() usage opens up many bug
possibilities due to the actual timeout evaluation's open-coded nature.
Issue ##50611 is one example.
- Some users store the returned value in a signed variable, others in
an unsigned one, making the comparison with UINT64_MAX (corresponding
to K_FOREVER) wrong in the signed case.
- Some users compute the difference and store that in a signed variable
to compare against 0 which still doesn't work with K_FOREVER. And when
this difference is used as a timeout argument then the K_FOREVER
nature of the timeout is lost.
- Some users complexify their code by special-casing K_NO_WAIT and
K_FOREVER inline which is bad for both code readability and binary
size.
Let's introduce a better abstraction to deal with absolute timepoints
with an opaque type to be used with a well-defined API.
The word "timeout" was avoided in the naming on purpose as the timeout
namespace is quite crowded already and it is preferable to make a
distinction between relative time periods (timeouts) and absolute time
values (timepoints).
A few stacks are also adjusted as they were too tight on X86.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>