I added fanotify_mark to sysdeps/unix/sysv/linux/sh/syscalls.list, and did a clean build, which created misc/fanotify_mark.*. Then, I applied changes to fanotify_mark in that syscalls.list. Upon rebuilding in the existing build tree, sysd-syscalls got updated, but misc/fanotify_mark.* did not, so I manually had to delete these to get them rebuilt.