libstdc++ bootstrap failure after r261525

[Martin Sebor]

Bootstrap fails in libstdc++ with the following error.
I haven't investigated it much except to take a peek
at recent libstdc++ commits where r261525 looks like it
introduced __glibcxx_check_can_increment_range, so it
seems like it might have something to do with it.  I don't
see a __glibcxx_requires_can_increment_range macro defined
anywhere in the patch so maybe it's a typo?  Francois, can
you please see what's going on?

/opt/notnfs/msebor/build/gcc-86114/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/stl_algobase.h:452:45: 
error: ‘__glibcxx_requires_can_increment_range’ was not declared in this 
scope
        __glibcxx_requires_can_increment_range(__first, __last, __result);

Thanks
Martin