cbfstool: Add option to ignore section in add-stage

Allow add-stage to have an optional parameter for ignoring any section. This is
required to ensure proper operation of elf_to_stage in case of loadable segments
with zero filesize.

Change-Id: I49ad62c2a4260ab9cec173c80c0f16923fc66c79
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: http://review.coreboot.org/7304
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>

util/cbfstool/common.h

@@ -139,7 +139,8 @@ int parse_flat_binary_to_payload(const struct buffer *input,
 				 comp_algo algo);
 /* cbfs-mkstage.c */
 int parse_elf_to_stage(const struct buffer *input, struct buffer *output,
-		       uint32_t arch, comp_algo algo, uint32_t *location);
+		       uint32_t arch, comp_algo algo, uint32_t *location,
+		       const char *ignore_section);
 
 void print_supported_filetypes(void);