cbfstool: have decompress functions provide ouput data size

Currently cbfs stage files that are compressed do not have
the decompressed size readily available. Therefore there's
no good way to know actual size of data after it is
decompressed. Optionally return the decompressed data size
if requested.

Change-Id: If371753d28d0ff512118d8bc06fdd48f4a0aeae7
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/12173
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/cbfstool/cbfs_image.c

@@ -692,7 +692,7 @@ int cbfs_export_entry(struct cbfs_image *image, const char *entry_name,
 	buffer.data = malloc(decompressed_size);
 	buffer.size = decompressed_size;
 	if (decompress(CBFS_SUBHEADER(entry), ntohl(entry->len),
-		buffer.data, buffer.size)) {
+		buffer.data, buffer.size, NULL)) {
 		ERROR("decompression failed for %s\n", entry_name);
 		return -1;
 	}