Describe the bug

I'm installing the most recent ROOT 6.22.06 from source archive on Arch Linux. At progress around 60% the compilation fails suggesting to look for details in

XROOTD-prefix/src/XROOTD-stamp/XROOTD-build-err.log

CMake Error at /opt/root/build-root-6.22.06/XROOTD-prefix/src/XROOTD-stamp/XROOTD-build-Release.cmake:49 (message):
Command failed: 2
'/usr/bin/make'
See also
/opt/root/build-root-6.22.06/XROOTD-prefix/src/XROOTD-stamp/XROOTD-build-*.log
make[2]: *** [CMakeFiles/XROOTD.dir/build.make:131: XROOTD-prefix/src/XROOTD-stamp/XROOTD-build] Error 1
make[1]: *** [CMakeFiles/Makefile2:7256: CMakeFiles/XROOTD.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....

The file contains this infomation:

[I] No git repository info found. Trying to interpret VERSION_INFO
[I] src/XrdVersion.hh successfully generated
/opt/root/build-root-6.22.06/XROOTD-prefix/src/XROOTD/src/XrdPosix/XrdPosix.cc: In function ‘int XrdPosix_Fstat(int, stat*)’:
/opt/root/build-root-6.22.06/XROOTD-prefix/src/XROOTD/src/XrdPosix/XrdPosix.cc:379:27: error: ‘_STAT_VER’ was not declared in this scope
379 | : Xunix.Fstat64(_STAT_VER, fildes, (struct stat64 )buf));
| ^~~~~~~~~
/opt/root/build-root-6.22.06/XROOTD-prefix/src/XROOTD/src/XrdPosix/XrdPosix.cc: In function ‘int XrdPosix_Lstat(const char, stat*)’:
/opt/root/build-root-6.22.06/XROOTD-prefix/src/XROOTD/src/XrdPosix/XrdPosix.cc:563:27: error: ‘_STAT_VER’ was not declared in this scope
563 | ? Xunix.Lstat64(_STAT_VER, path, (struct stat64 )buf)
| ^~~~~~~~~
/opt/root/build-root-6.22.06/XROOTD-prefix/src/XROOTD/src/XrdPosix/XrdPosix.cc: In function ‘int XrdPosix_Stat(const char, stat*)’:
/opt/root/build-root-6.22.06/XROOTD-prefix/src/XROOTD/src/XrdPosix/XrdPosix.cc:891:26: error: ‘_STAT_VER’ was not declared in this scope
891 | ? Xunix.Stat64(_STAT_VER, path, (struct stat64 *)buf)
| ^~~~~~~~~
make[5]: *** [src/CMakeFiles/XrdPosixPreload.dir/build.make:108: src/CMakeFiles/XrdPosixPreload.dir/XrdPosix/XrdPosix.cc.o] Error 1
make[4]: *** [CMakeFiles/Makefile2:1838: src/CMakeFiles/XrdPosixPreload.dir/all] Error 2
make[3]: *** [Makefile:149: all] Error 2

I disabled xrootd as was suggested on the forum with

cmake -Dxrootd=OFF -Dbuiltin_xrootd=OFF <source_dir>

Expected behavior

xrootd should compile or, if it's not needed, be optional (not default). I'm not sure whether I need that.

To Reproduce

1. Download and unpack a source .tar.gz, create and cd the build directory.
2. cmake --build . --target install -- -j15

Setup

1. 6.22.06
2. Arch Linux.
3. Source package from site, root_v6.22.06.source.tar.gz

Additional context

There exist reports on xrootd, but not connected to this variable.
I have to say that I failed to compile without xrootd, but it is probably another issue.