skeleton: make /run a proper directory/filesystem

Making /var/run and /run symlinks to /tmp is bad since the underlying
tmpfs filesystem is mode 1777 which leads to possible security attack
vectors via badly owned/mask-mode pidfiles and state files residing there.

So make /run a proper directory with /var/run symlinked to it.
Eventually all startup scripts and state info should be pointed to /run
directly as per the linux fhs and good practice.

Add a tmpfs filesystem entry for /run so that busybox inittab, systemv
inittab and systemd automount mounts it there to avoid breaking the
system.

While at it fix inconsistent spacing in /etc/fstab by using tabs and
drop the "static file system information" header whatever that means.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

system/skeleton/etc/fstab

@@ -1,9 +1,8 @@
-# /etc/fstab: static file system information.
-#
-# <file system> <mount pt>     <type>	<options>         <dump> <pass>
-/dev/root       /              ext2	rw,noauto         0      1
-proc		/proc	       proc     defaults	  0	 0
-devpts		/dev/pts       devpts   defaults,gid=5,mode=620	  0	 0
-tmpfs           /dev/shm       tmpfs    mode=0777         0      0
-tmpfs           /tmp           tmpfs    mode=1777         0      0
-sysfs		/sys	       sysfs    defaults	  0	 0
+# <file system>	<mount pt>	<type>	<options>	<dump>	<pass>
+/dev/root	/		ext2	rw,noauto	0	1
+proc		/proc		proc	defaults	0	0
+devpts		/dev/pts	devpts	defaults,gid=5,mode=620	0	0
+tmpfs		/dev/shm	tmpfs	mode=0777	0	0
+tmpfs		/tmp		tmpfs	mode=1777	0	0
+tmpfs		/run		tmpfs	mode=0755,nosuid,nodev	0	0
+sysfs		/sys		sysfs	defaults	0	0

system/skeleton/run

@@ -1 +0,0 @@
-tmp

system/skeleton/var/run

@@ -1 +1 @@
-../tmp
+../run