unix: use correct file name in comment

Change-Id: Ib05fbd6f1dca630a3ac596f88373756797d8c27e
Reviewed-on: https://go-review.googlesource.com/c/sys/+/212298
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
diff --git a/unix/fcntl.go b/unix/fcntl.go
index 39c03f1..df2fc50 100644
--- a/unix/fcntl.go
+++ b/unix/fcntl.go
@@ -9,7 +9,7 @@
 import "unsafe"
 
 // fcntl64Syscall is usually SYS_FCNTL, but is overridden on 32-bit Linux
-// systems by flock_linux_32bit.go to be SYS_FCNTL64.
+// systems by fcntl_linux_32bit.go to be SYS_FCNTL64.
 var fcntl64Syscall uintptr = SYS_FCNTL
 
 // FcntlInt performs a fcntl syscall on fd with the provided command and argument.