apparently I can't remember open_memstream(3) so I always* reach for
fmemopen(3) only to realize it's not the function I want.

* always, well, two times probably.  but still, it's weird.

Since the two functions are closely related (one operates on a given,
fixed size buffer, the other on a dynamically allocated one) I think a
Xr is not a bad idea.  fmemopen(3) already references open_memstream(3).
(plus i think fmemopen is a more memorable name than open_memstream.)

SEE ALSO still fits in a single line.

thoughts?

diff /usr/src
path + /usr/src
commit - 93132b6cfa71f1351ecc1c8aaa0a62d5c278e1da
blob - a0ce544d8a7a6ad542eea2c6639d7d936999a71a
file + lib/libc/stdio/fmemopen.3
--- lib/libc/stdio/fmemopen.3
+++ lib/libc/stdio/fmemopen.3
@@ -184,7 +184,8 @@ specified for the routine
 .Xr fflush 3 ,
 .Xr fopen 3 ,
 .Xr funopen 3 ,
-.Xr malloc 3
+.Xr malloc 3 ,
+.Xr open_memstream 3
 .Sh STANDARDS
 The function
 .Fn fmemopen