Implement the class submdspan_mapping_result and add it to the std
module.
PR libstdc++/110352
libstdc++-v3/ChangeLog:
* include/std/mdspan (submdspan_mapping_result): New class.
* src/c++23/std.cc.in (submdspan_mapping_result): Add.
Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
Signed-off-by: Luc Grosheintz <luc.grosheintz@gmail.com>
e269268e45