3377: Add Thread Safety Analysis r=heinrich5991 a=def-
https://clang.llvm.org/docs/ThreadSafetyAnalysis.html
## Checklist
- [ ] Tested the change ingame
- [ ] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test if it works standalone, system.c especially
- [ ] Considered possible null pointers and out of bounds array indexing
- [ ] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)
3487: Fix centisecs rounding in str_time_float r=heinrich5991 a=def-
<!-- What is the motivation for the changes of this pull request -->
## Checklist
- [ ] Tested the change ingame
- [ ] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test if it works standalone, system.c especially
- [ ] Considered possible null pointers and out of bounds array indexing
- [ ] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)
Co-authored-by: def <dennis@felsin9.de>
Purely automatic change. In case of conflict with this change, apply the
other change and rerun the formatting to restore it:
$ python scripts/fix_style.py
Quoting the man page of vsnprintf:
RETURN VALUE
Upon successful return, these functions return the number of characters printed
(excluding the null byte used to end output to strings).
The functions snprintf() and vsnprintf() do not write more than size bytes (including
the terminating null byte ('\0')). If the output was truncated due to this limit,
then the return value is the number of characters (excluding the terminating null
byte) which would have been written to the final string if enough space had been
available. Thus, a return value of size or more means that the output was truncated.
(See also below under NOTES.)
If an output error is encountered, a negative value is returned.
[...]
The glibc implementation of the functions snprintf() and vsnprintf() conforms to the
C99 standard, that is, behaves as described above, since glibc version 2.1. Until
glibc 2.0.6, they would return -1 when the output was truncated.