bitbake.conf: drop VOLATILE_TMP_DIR, use FILESYSTEM_PERMS_TABLES instead

* Drop VOLATILE_TMP_DIR, use FILESYSTEM_PERMS_TABLES instead. By default,
FILESYSTEM_PERMS_TABLES ?=  "files/fs-perms.txt \
                             files/fs-perms-volatile-log.txt \
                             files/fs-perms-volatile-tmp.txt"
it contains 'files/fs-perms-volatile-tmp.txt', which means volatile tmp
is enabled. User can disable volatile tmp by remove
'files/fs-perms-volatile-tmp.txt' from FILESYSTEM_PERMS_TABLES.
* If volatile tmp is disabled, both /tmp and /var/tmp are persistent

(From OE-Core rev: 8d1ae67b89c45f78162e070228086c7ef88c3264)

Signed-off-by: Changqing Li <changqing.li@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/files/fs-perms-volatile-tmp.txt

@@ -0,0 +1,38 @@
+# This file contains a list of files and directories with known permissions.
+# It is used by the packaging class to ensure that the permissions, owners and
+# group of listed files and directories are in sync across the system.
+#
+# The format of this file 
+#
+#<path>	<mode>	<uid>	<gid>	<walk>	<fmode>	<fuid>	<fgid>
+#
+# or
+#
+#<path> link <target>
+#
+# <path>: directory path
+# <mode>: mode for directory
+# <uid>:  uid for directory
+# <gid>:  gid for directory
+# <walk>: recursively walk the directory?  true or false
+# <fmode>: if walking, new mode for files
+# <fuid>:  if walking, new uid for files
+# <fgid>:  if walking, new gid for files
+# <target>: turn the directory into a symlink point to target
+#
+# in mode, uid or gid, a "-" means don't change any existing values
+#
+# /usr/src		0755	root	root	false	-	-	-
+# /usr/share/man	0755	root	root	true	0644	root	root
+
+# Note: all standard config directories are automatically assigned "0755 root root false - - -"
+
+# Documentation should always be corrected
+
+# Items from base-files
+# Links
+${localstatedir}/tmp	link	volatile/tmp
+
+# Special permissions from base-files
+# Set 1777
+${localstatedir}/volatile/tmp	01777	root	root	false - - -

meta/files/fs-perms.txt

@@ -46,7 +46,6 @@ ${includedir}		0755	root	root	true	0644	root	root
 # Links
 ${localstatedir}/run	link	/run
 ${localstatedir}/lock	link	/run/lock
-${localstatedir}/tmp	link	volatile/tmp
 
 /home				0755	root	root	false - - -
 /srv				0755	root	root	false - - -
@@ -56,7 +55,6 @@ ${localstatedir}/local		0755	root	root	false - - -
 # Special permissions from base-files
 # Set 1777
 /tmp				01777	root	root	false - - -
-${localstatedir}/volatile/tmp	01777	root	root	false - - -
 
 # Set 0700
 ${ROOT_HOME}			0700	root	root	false - - -