correctly mount tmpfs as /tmp in recovery

The syntax of init's mount command changed in April 2008 but
recovery's init.rc was never updated, so recovery's /tmp has been on
the root fs all this time.  Fix.

Also add /system/bin to the PATH in recovery, which is handy for
debugging.

Change-Id: I39f7ae435a8ce3bad691e4b7c307db0bd8de1302

etc/init.rc

@@ -12,7 +12,7 @@ on early-init
     start healthd
 
 on init
-    export PATH /sbin
+    export PATH /sbin:/system/bin
     export ANDROID_ROOT /system
     export ANDROID_DATA /data
     export EXTERNAL_STORAGE /sdcard
@@ -23,7 +23,7 @@ on init
     mkdir /system
     mkdir /data
     mkdir /cache
-    mount /tmp /tmp tmpfs
+    mount tmpfs tmpfs /tmp
 
     chown root shell /tmp
     chmod 0775 /tmp