This shows up as an assertion failure when sprintf is called with
a specifier like "%.8g" and libquadmath is linked in:
Fatal glibc error: printf_buffer_as_file.c:31
(__printf_buffer_as_file_commit): assertion failed:
file->stream._IO_write_ptr <= file->next->write_end
Fix this by detecting pointer wraparound in __vsprintf_internal
and saturate the addition to the end of the address space instead.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>