These marker comments are in every other zsyscall_*.go file generated by
mksyscall.pl. Also add them to the files generated by mksyscall_libc.pl
used for aix and solaris.

Change-Id: I7fd125df3549d83c658bbe7424861c76c024f2e5
Reviewed-on: https://go-review.googlesource.com/c/141037
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>