Add dumpimage, a tool to extract data from U-Boot images

Given a multi-file image created through the mkimage's -d option:

  $ mkimage -A x86 -O linux -T multi -n x86 -d vmlinuz:initrd.img:System.map \
  multi.img

  Image Name:   x86
  Created:      Thu Jul 25 10:29:13 2013
  Image Type:   Intel x86 Linux Multi-File Image (gzip compressed)
  Data Size:    13722956 Bytes = 13401.32 kB = 13.09 MB
  Load Address: 00000000
  Entry Point:  00000000
  Contents:
     Image 0: 4040128 Bytes = 3945.44 kB = 3.85 MB
     Image 1: 7991719 Bytes = 7804.41 kB = 7.62 MB
     Image 2: 1691092 Bytes = 1651.46 kB = 1.61 MB

It is possible to perform the innverse operation -- extracting any file from
the image -- by using the dumpimage's -i option:

  $ dumpimage -i multi.img -p 2 System.map

Although it's feasible to retrieve "data files" from image through scripting,
the requirement to embed tools such 'dd', 'awk' and 'sed' for this sole purpose
is cumbersome and unreliable -- once you must keep track of file sizes inside
the image. Furthermore, extracting data files using "dumpimage" tool is faster
than through scripting.

Signed-off-by: Guilherme Maciel Ferreira <guilherme.maciel.ferreira@gmail.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index 7310c4e..c83cf3e 100644
--- a/Makefile
+++ b/Makefile
@@ -797,6 +797,7 @@
 	       $(obj)tools/envcrc					  \
 	       $(obj)tools/gdb/{astest,gdbcont,gdbsend}			  \
 	       $(obj)tools/gen_eth_addr    $(obj)tools/img2srec		  \
+	       $(obj)tools/dump{env,}image		  \
 	       $(obj)tools/mk{env,}image   $(obj)tools/mpc86x_clk	  \
 	       $(obj)tools/mk{$(BOARD),}spl				  \
 	       $(obj)tools/mxsboot					  \