ifdfake - Create an IFD with just a section layout

This new tool called `ifdfake` just creates an empty Intel Firmware
Descriptor (IFD) and writes the IFD signature plus the section layout
given on the command line.

    usage: ifdfake [(-b|-m|-g|-p) <start>:<end>]... <output file>

       -b | --bios       <start>:<end>   BIOS region
       -m | --me         <start>:<end>   Intel ME region
       -g | --gbe        <start>:<end>   Gigabit Ethernet region
       -p | --platform   <start>:<end>   Platform Data region
       -h | --help                       print this help

    <start> and <end> bounds are given in Bytes, the <end> bound is inclusive.
    All regions must be multiples of 4K in size and 4K aligned.
    The descriptor region always resides in the first 4K.

    An IFD created with ifdfake won't work as a replacement for a real IFD.
    Never try to flash such an IFD to your board!

The output of ifdfake can be utilized to build an image with just the
later added sections (like coreboot itself) being valid. The resulting
image can then be partially written to a machines flash ROM to just
update coreboot (i.e. the BIOS section).

Change-Id: I925b47cab5c6d490a79d684bdd7a7a45ac442640
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: http://review.coreboot.org/3523
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
diff --git a/.gitignore b/.gitignore
index e57e32f..0061152 100644
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