Description:

In gcc-10's libstdc++, condition variables require the function `pthread_mutex_clocklock`, which was introduced
in libc 2.30. However, the gcc 10.1.0-2 package depends on gcclibs 10.1.0-2, which includes glibc>=2.27. This
leaves 3 minors of glibc not upgraded by installing gcc-10.1.0-2.

Cf. announcement http://randombitsofuselessinformation.blogspot.com/2019/09/stdconditionvariable-will-work.html
Cf. patch https://gcc.gnu.org/legacy-ml/gcc-patches/2019-10/msg01118.html


Additional info:
* package version(s) 10.1.0-2
* config and/or log files etc.
* link to upstream bug report, if any

Steps to reproduce:

Upgrade gcc from version 9 to 10. Set glibc to 2.28. Compile this snippet:

```
#include <mutex>

int main() {
std::timed_mutex m;
if (m.try_lock()) {
m.unlock();
}
}
```

Results:

```
$ g++ xtofl.cpp
In file included from xtofl.cpp:1:
/usr/include/c++/10.1.0/mutex: In member function ‘bool std::timed_mutex::_M_clocklock(clockid_t, const __gthread_time_t&)’:
/usr/include/c++/10.1.0/mutex:270:17: error: ‘pthread_mutex_clocklock’ was not declared in this scope; did you mean ‘pthread_mutex_unlock’?
270 | { return !pthread_mutex_clocklock(&_M_mutex, clockid, &__ts); }
| ^~~~~~~~~~~~~~~~~~~~~~~
| pthread_mutex_unlock
/usr/include/c++/10.1.0/mutex: In member function ‘bool std::recursive_timed_mutex::_M_clocklock(clockid_t, const __gthread_time_t&)’:
/usr/include/c++/10.1.0/mutex:336:17: error: ‘pthread_mutex_clocklock’ was not declared in this scope; did you mean ‘pthread_mutex_unlock’?
336 | { return !pthread_mutex_clocklock(&_M_mutex, clockid, &__ts); }
| ^~~~~~~~~~~~~~~~~~~~~~~
| pthread_mutex_unlock
compilation terminated.
```