Mount `/dev/shm' (shared memory support).

svn path=/nixos/branches/fix-style/; revision=14172

boot/boot-stage-2-init.sh

@@ -69,6 +69,8 @@ mkdir -m 0755 -p /sys
 mount -t sysfs none /sys
 mkdir -m 0755 -p /dev
 mount -t tmpfs -o "mode=0755" none /dev
+mkdir -m 0777 /dev/shm
+mount -t tmpfs -o "rw,nosuid,nodev" tmpfs /dev/shm
 mkdir -m 0755 -p /dev/pts
 mount -t devpts none /dev/pts
 [ -e /proc/bus/usb ] && mount -t usbfs none /proc/bus/usb # uml doesn't have usb by default