On 7/24/20 10:36 AM, Zack Weinberg wrote:
> The symbol that was removed (_IO_file_flags) was never a documented
> part of the stdio interface.

True, though lots of programs want to know about stdio readahead and it's 
unfortunate that glibc and other C libraries don't provide a documented way to 
get it.

We have a Gnulib module for discovering stdio readahead. As seen here:

https://git.savannah.gnu.org/cgit/gnulib.git/tree/lib/freadahead.c#n36

Gnulib uses the guard "#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || 
__GNU_LIBRARY__ == 1" to be as portable as possible to various glibc-like 
libraries, so I suggest the attached minimal patch to C-Kermit.