syscall: Remove Linux system calls not available in older glibcs.

From-SVN: r180784

libgo/go/syscall/libcall_linux.go

@@ -186,8 +186,9 @@ func PtraceDetach(pid int) (errno int) { return ptrace(PTRACE_DETACH, pid, 0, 0)
 //sys	Faccessat(dirfd int, path string, mode uint32, flags int) (errno int)
 //faccessat(dirfd int, pathname *byte, mode int, flags int) int
 
-//sys	Fallocate(fd int, mode uint32, off int64, len int64) (errno int)
-//fallocate(fd int, mode int, offset Offset_t, len Offset_t) int
+// FIXME: Only in glibc 2.10 and later.
+// //sys	Fallocate(fd int, mode uint32, off int64, len int64) (errno int)
+// //fallocate(fd int, mode int, offset Offset_t, len Offset_t) int
 
 //sys	Fchmodat(dirfd int, path string, mode uint32, flags int) (errno int)
 //fchmodat(dirfd int, pathname *byte, mode Mode_t, flags int) int
@@ -223,8 +224,9 @@ func PtraceDetach(pid int) (errno int) { return ptrace(PTRACE_DETACH, pid, 0, 0)
 //sysnb	InotifyInit() (fd int, errno int)
 //inotify_init() int
 
-//sysnb	InotifyInit1(flags int) (fd int, errno int)
-//inotify_init1(flags int) int
+// FIXME: Only in glibc 2.9 and later.
+// //sysnb	InotifyInit1(flags int) (fd int, errno int)
+// //inotify_init1(flags int) int
 
 //sysnb	InotifyRmWatch(fd int, watchdesc uint32) (success int, errno int)
 //inotify_rm_watch(fd int, wd uint32) int
@@ -298,8 +300,9 @@ func Splice(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n i
 // //sys	Statfs(path string, buf *Statfs_t) (errno int)
 // //statfs(path *byte, buf *Statfs_t) int
 
-//sys	SyncFileRange(fd int, off int64, n int64, flags int) (errno int)
-//sync_file_range(fd int, off Offset_t, n Offset_t, flags uint) int
+// FIXME: Only in glibc 2.6 and later.
+// //sys	SyncFileRange(fd int, off int64, n int64, flags int) (errno int)
+// //sync_file_range(fd int, off Offset_t, n Offset_t, flags uint) int
 
 // FIXME: mksysinfo Sysinfo_t
 // //sysnb	Sysinfo(info *Sysinfo_t) (errno int)