config/ChangeLog:
PR bootstrap/96612
* ax_cxx_compile_stdcxx.m4: Add fourth argument to check also
the CXX_FOR_BUILD compiler.
ChangeLog:
PR bootstrap/96612
* configure.ac: Run AX_CXX_COMPILE_STDCXX also for ${build} compiler,
if not the same as ${host}.
* configure: Regenerate.