Makefile: fix build issue on old gcc
The previous fcf-protection fix broke the old gcc (older than
gcc 8 which is common on Ubuntu 18.04 and older distributions).
We only add fcf-protection=none for gcc8 and newer.
@@ -102,7 +102,9 @@ endif
# https://bugs.launchpad.net/ubuntu/+source/gcc-9/+bug/1830961
#
# We disable the -fcf-protection in ACRN build.
+ifeq (true, $(shell [ $(GCC_MAJOR) -gt 8 ] && echo true))
CFLAGS += -fcf-protection=none
+endif
ASFLAGS += -m64 -nostdinc -nostdlib
