GNUstep base build fails at configure step with clang 22

Hi all,

Our CI runs Ubuntu, Fedora and Arch source builds of the GNUstep 
libraries as part of building Oolite (because we need fixes on the 
master branch that are not in the last stable release). The Arch one 
started to fail at the configure stage building GNUstep base:

|checking whether objc really works... yes configure: error: Your 
compiler does not appear to implement the -fconstant-string-class option 
needed for support of strings. Please check for a more recent version or 
consider using --enable-nxconstantstring checking if the compiler 
supports -fconstant-string-class... no|

The issue seems to be that Arch has moved from clang 21 to 22. Has 
anyone else had this problem when building with clang 22? I have created 
an issue: https://github.com/gnustep/libs-base/issues/589

Cheers,
Mike