cbfstool: add optional -m ARCH to extract

In order to prepare allowing for one to extract a stage
into an ELF file provide an optional -m ARCH option. This
allows one to indicate to cbfstool what architecture type
the ELF file should be in.

Longer term each stage and payload will have an attribute
associated with it which indicates the attributes of
the executable.

Change-Id: Id190c9719908afa85d5a3b2404ff818009eabb4c
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/12217
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

util/cbfstool/cbfs_image.c

@@ -725,7 +725,7 @@ static int cbfs_stage_decompress(struct buffer *buff)
 }
 
 int cbfs_export_entry(struct cbfs_image *image, const char *entry_name,
-		      const char *filename)
+		      const char *filename, unused uint32_t arch)
 {
 	struct cbfs_file *entry = cbfs_get_entry(image, entry_name);
 	struct buffer buffer;