Nearly complete rewrite of cgpt tool.

This fixes a number of bugs, adds a bunch of commands, and essentially makes
cgpt ready to use as a replacement for gpt. Still to do is to add commands
and options that will let it generated intentionally bad partitions, for use
in testing.

Review URL: http://codereview.chromium.org/2719008
diff --git a/Makefile b/Makefile
index e30d716..853bfbf 100644
--- a/Makefile
+++ b/Makefile
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 export CC ?= gcc
+export CXX ?= g++
 export CFLAGS = -Wall -DNDEBUG -O3 -Werror
 export TOP = $(shell pwd)
 export FWDIR=$(TOP)/vboot_firmware
@@ -14,7 +15,7 @@
 export FWLIB=$(FWDIR)/vboot_fw.a
 export HOSTLIB=$(HOSTDIR)/vboot_host.a
 
-SUBDIRS=vboot_firmware misclibs host vfirmware vkernel utility tests
+SUBDIRS=vboot_firmware misclibs host vfirmware vkernel utility cgpt tests
 
 all:
 	set -e; \
@@ -30,6 +31,7 @@
 
 install:
 	$(MAKE) -C utility install
+	$(MAKE) -C cgpt install
 
 runtests:
 	$(MAKE) -C tests runtests