libpayload/libc/getopt_long: Use common GCD

TEST=emerge-geralt libpayload

Change-Id: Ib9dd1d2f658d4411c36d0198774819690686a393
Signed-off-by: Yidi Lin <yidilin@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78887
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

payloads/libpayload/libc/Makefile.inc

@@ -46,4 +46,5 @@ endif
 
 ifeq ($(CONFIG_LP_LIBC),y)
 libc-srcs += $(coreboottop)/src/commonlib/bsd/elog.c
+libc-srcs += $(coreboottop)/src/commonlib/bsd/gcd.c
 endif