Add `process_pid` field to `timer_internal_t` struct.
This field is used by the `alarm()` function to specify the PID of the process
to which the `SIGALRM` signal should be delivered.
Workaround for a bug inside `cbindgen`. For some reason it does not like
us exporting constants that depend on other constants that are *not*
defined as a part of the same module.
`timespec_get` and `timespec_getres` are both C23 functions. They're
similar to the POSIX functions `clock_gettime` and `clock_getres`, but
both sets of functions define extra, exclusive features. I didn't
implement the extra features yet, partially because Redox doesn't seem
to support them yet either.
Our strptime implementation uses subformatting to handle specifiers that
expand to other specifiers. For example, '%T' expands to "%H:%M%:%S".
Relibc calls strptime again to handle '%T' by expanding it.
However, our strptime zeroes out struct tm which clobbers old values. If
strptime is called with a format string like "%D%t%T", the set values
for '%D' are clobbered.
Zeroing out the struct is extra, unneeded work as well. The user may
want to preserve old values. We don't read from struct tm so we don't
have to worry about invalid values. Finally, `musl` and `glibc` don't
clear the values either so we can default to their behavior.
* %T is implemented but untested for now (we lack strptime tests)
* I switched some unexported, immutable statics to const as it's a
better fit
* parse_am_pm() now correctly strips prefixed whitespace AND doesn't
allocate heap memory
Speedy_Lex