dpkg 1.22.0 started adding -mbranch-protection=standard on arm64. This
breaks cross builds for arm64 which add CFLAGS to CC_FOR_BUILD
invocations as well because CFLAGS are assembled for the host
architecture and might break build architecture compiler invocations.

Linux 6.4, A311D support

See merge request !9

linux/build.sh: re-enable copying pocket reform dts (disabled in 'initial support for meson-g12b-bananapi-cm4-mnt-reform2')