gmessages.c compile failure with -Werror=unused-result

As per this conda-forge build log, we're seeing a compile failure due to an unused-result issue:

../glib/gmessages.c: In function 'write_string_sized':
../glib/gmessages.c:616:5: error: ignoring return value of 'fwrite' declared with attribute 'warn_unused_result' [-Werror=unused-result]
   616 |     fwrite (string, 1, length, stream);
       |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This code has been around for a very long time, so I guess maybe someone only added the unused-result annotation to fwrite recently?

This is gcc 10.4 on Linux (x86_64).