Description of problem:
Packages libre and baresip fail to build from source in Fedora Rawhide.

Version-Release number of selected component (if applicable):
baresip-4.1.0-1.fc44
libre-4.1.0-1.fc44

Steps to Reproduce:
koji build --scratch f44 baresip-4.1.0-1.fc44.src.rpm
koji build --scratch f44 libre-4.1.0-1.fc44.src.rpm

Additional info:
These packages are tracked by Koschei. See:
https://koschei.fedoraproject.org/package/baresip
https://koschei.fedoraproject.org/package/libre

baresip and libre started to fail with this glibc update:
https://koschei.fedoraproject.org/build/21603986
https://koschei.fedoraproject.org/build/21609981

Compilation error:
In file included from /usr/include/re/re.h:60,
                 from /builddir/build/BUILD/baresip-4.1.0-build/baresip-4.1.0/modules/sdl/sdl.c:8:
/usr/include/re/re_thread.h:45:9: warning: ‘ONCE_FLAG_INIT’ redefined
   45 | #define ONCE_FLAG_INIT PTHREAD_ONCE_INIT
      |         ^~~~~~~~~~~~~~
In file included from /usr/include/stdlib.h:1162,
                 from /usr/include/SDL2/SDL_stdinc.h:42,
                 from /usr/include/SDL2/SDL_main.h:25,
                 from /usr/include/SDL2/SDL.h:31,
                 from /builddir/build/BUILD/baresip-4.1.0-build/baresip-4.1.0/modules/sdl/sdl.c:7:
/usr/include/bits/types/once_flag.h:25:9: note: this is the location of the previous definition
   25 | #define ONCE_FLAG_INIT __ONCE_FLAG_INIT
      |         ^~~~~~~~~~~~~~
/usr/include/re/re_thread.h:46:24: error: conflicting types for ‘once_flag’; have ‘pthread_once_t’ {aka ‘int’}
   46 | typedef pthread_once_t once_flag;
      |                        ^~~~~~~~~
/usr/include/bits/types/once_flag.h:24:21: note: previous declaration of ‘once_flag’ with type ‘once_flag’
   24 | typedef __once_flag once_flag;
      |                     ^~~~~~~~~
/usr/include/re/re_thread.h:132:6: error: conflicting types for ‘call_once’; have ‘void(int *, void (*)(void))’
  132 | void call_once(once_flag *flag, void (*func)(void));
      |      ^~~~~~~~~
/usr/include/stdlib.h:1166:13: note: previous declaration of ‘call_once’ with type ‘void(once_flag *, void (*)(void))’
 1166 | extern void call_once (once_flag *__flag, void (*__func)(void));
      |             ^~~~~~~~~

Looks like it's a new conflict between libre (/usr/include/re/re_thread.h) and glibc (/usr/include/bits/types/once_flag.h).