util/cbmem: Use commonlib ipchksum() algorithm

This patch switches the cbmem utility from its own IP checksum
implementation to the commonlib version (which is good because the old
one had a couple of bugs: doesn't work on odd sizes and may overflow
its carry accumulator with input larger than 64K).

Change-Id: I0bef2c85c37ddd3438b7ac6389e9daa3e4955b31
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80256
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Yidi Lin <yidilin@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/cbmem/Makefile

@@ -4,6 +4,7 @@
 PROGRAM   = cbmem
 TOP      ?= $(abspath ../..)
 ROOT      = $(TOP)/src
+COMMONLIB = $(ROOT)/commonlib
 CC       ?= $(CROSS_COMPILE)gcc
 INSTALL  ?= /usr/bin/env install
 PREFIX   ?= /usr/local
@@ -13,14 +14,14 @@ CFLAGS   += -Wall -Wextra -Wmissing-prototypes -Wshadow $(WERROR)
 CPPFLAGS += -I . -I $(ROOT)/commonlib/include -I $(ROOT)/commonlib/bsd/include
 CPPFLAGS += -include $(ROOT)/commonlib/bsd/include/commonlib/bsd/compiler.h
 
-OBJS = $(PROGRAM).o
+OBJS = $(PROGRAM).o $(COMMONLIB)/bsd/ipchksum.o
 
 all: $(PROGRAM)
 
 $(PROGRAM): $(OBJS)
 
 clean:
-	rm -f $(PROGRAM) *.o .dependencies *~ junit.xml
+	rm -f $(PROGRAM) $(OBJS:.c=.o) .dependencies *~ junit.xml
 
 install: $(PROGRAM)
 	$(INSTALL) -d $(DESTDIR)$(PREFIX)/sbin/