busybox: add grep to temporary links during uninstall

In the busybox package prerm we set up some temporary links and modify
PATH so that certain utilities are provided for the purpose of running
update-alternatives; if grep is not among these then you get errors when
removing busybox, so add a temporary link for grep as well.

(From OE-Core rev: 013eca09c863862cc6b7ee3bc22923bf8fb42956)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/busybox/busybox.inc

@@ -270,6 +270,7 @@ pkg_prerm_${PN} () {
 	ln -s /bin/busybox $tmpdir/rm
 	ln -s /bin/busybox $tmpdir/sed
 	ln -s /bin/busybox $tmpdir/sort
+	ln -s /bin/busybox $tmpdir/grep
 	export PATH=$PATH:$tmpdir
 
 	while read link

meta/recipes-core/busybox/busybox_1.18.5.bb

@@ -1,5 +1,5 @@
 require busybox.inc
-PR = "r1"
+PR = "r2"
 
 SRC_URI = "http://www.busybox.net/downloads/busybox-${PV}.tar.bz2;name=tarball \
            file://udhcpscript.patch \