[compiler-rt][sanitizer] sanitizer_platform_limits_posix.cpp uses struct termio, which will be removed in glibc-2.42

[hhoffstaette]

Glibc-2.42 will remove <termio.h> and struct termio (commit), which have been outdated since before Linux existed.
A test run in Gentoo's CI found a compilation error in LLVM, which can be found here and can be traced to this location:

#if SANITIZER_GLIBC || SANITIZER_ANDROID
  unsigned struct_termio_sz = sizeof(struct termio);
#endif

While it will be some time until glibc-2.42 ships, it seems prudent to get ahead of this, especially since the remaining use of struct termio seems like an oversight.

[hpax]

So I made a comment on this a bit ago, but it seems to have gotten eaten somehow.

There are additional problems: the handling of struct termios is completely wrong as currently written. The structure defined in <termios.h> comes from glibc, not from the kernel, but the ioctls of course use the kernel definition.

Furthermore, most, but not all, Linux platforms have a second version of these ioctls and a new struct termios2.

I think the best way to deal with it might be something like this:
sanitizer.diff.txt

This is compile tested only.

[hpax]

Note that by getting struct termio from <linux/termios.h> then there is no reason to conditionalize these ioctls.