futility: the show command can traverse all file types

It doesn't yet handle block devices, but it can display normal files
containing a entire BIOS image, a GBB, a VBLOCK, a .vbpubk, a .vblock,
and a firmware preamble (VbFirmwarePreambleHeader).

The command-line options are not well-documented.

BUG=chromium:224734
BRANCH=ToT
TEST=make runtests

Change-Id: I181f6331ae23599302bbaee3f270e8af9586cf06
Reviewed-on: https://chromium-review.googlesource.com/216032
Commit-Queue: Bill Richardson <wfrichar@chromium.org>
Tested-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
diff --git a/Makefile b/Makefile
index ec551b3..ace39eb 100644
--- a/Makefile
+++ b/Makefile
@@ -534,7 +534,8 @@
 FUTIL_STATIC_SRCS = \
 	futility/futility.c \
 	futility/cmd_dump_fmap.c \
-	futility/cmd_gbb_utility.c
+	futility/cmd_gbb_utility.c \
+	futility/misc.c
 
 FUTIL_SRCS = \
 	$(FUTIL_STATIC_SRCS) \
@@ -544,7 +545,9 @@
 	futility/cmd_vbutil_kernel.c \
 	futility/cmd_vbutil_key.c \
 	futility/cmd_vbutil_keyblock.c \
-	futility/cmd_verify_kernel.c
+	futility/cmd_verify_kernel.c \
+	futility/cmd_show.c \
+	futility/traversal.c
 
 ifneq (${VBOOT2},)
 FUTIL_SRCS += \