This is a copy of http://golang.org/cl/9870 in the syscall package.

This is in preparation for arm64 support, as the arm64 Linux kernel
does not have an inotify_init system call, only inotify_init1.

Update golang/go#10150.

Change-Id: I9224a094af79adbb2f5714ad977b195d5a941eb0
Reviewed-on: https://go-review.googlesource.com/10036Reviewed-by: Rob Pike <r@golang.org>