mkimage fails to build on some systems if sed is not installed, add a dependency to fix parallel build issues

SVN-Revision: 21210

tools/Makefile

@@ -46,6 +46,7 @@ $(curdir)/automake/compile := $(curdir)/m4/install $(curdir)/autoconf/install
 $(curdir)/mpc/compile := $(curdir)/gmp/install
 $(curdir)/mpfr/compile := $(curdir)/gmp/install
 $(curdir)/mtd-utils/compile := $(curdir)/libuuid/install
+$(curdir)/mkimage/compile := $(curdir)/sed/install
 
 $(curdir)/builddirs := $(tools-y) $(tools-dep) $(tools-)
 $(curdir)/builddirs-default := $(tools-y)