rename ARMBIAN_PREFER_NATIVE_ARMHF → PREFER_NATIVE_ARMHF

Match the naming convention of sibling build switches in the same section
(KERNEL_BTF, USE_CCACHE, ARTIFACT_IGNORE_CACHE, …) which carry no prefix.
Suggested in armbian/documentation#921.

Assisted-by: Claude:claude-opus-4.7

Author: iav

extensions/arm64-compat-vdso.sh

@@ -5,7 +5,7 @@
 # natively at full speed. One concrete use case is Armbian's rootfs phase: on
 # such a host, armhf chroot / package post-install steps run native instead of
 # through qemu-user-static (~10× faster). See lib/functions/rootfs/qemu-static.sh
-# and the ARMBIAN_PREFER_NATIVE_ARMHF build switch.
+# and the PREFER_NATIVE_ARMHF build switch.
 #
 # Note: aarch64 silicon without 32-bit ARM userspace support at EL0 (notably
 # Apple M-series) cannot run armhf even with this kernel option enabled.

lib/functions/rootfs/qemu-static.sh

@@ -194,7 +194,7 @@ function prepare_host_binfmt_qemu_cross() {
 
 function prepare_host_binfmt_qemu_cross_arm64_host_armhf_target() {
 	declare armhf_probe="/usr/arm-linux-gnueabihf/lib/ld-linux-armhf.so.3"
-	declare prefer_native="${ARMBIAN_PREFER_NATIVE_ARMHF:-yes}"
+	declare prefer_native="${PREFER_NATIVE_ARMHF:-yes}"
 	declare qemu_arm_was_enabled=0
 
 	# Snapshot qemu-arm state — drives both COMPAT probe and trust-existing.
@@ -225,7 +225,7 @@ function prepare_host_binfmt_qemu_cross_arm64_host_armhf_target() {
 		fi
 	fi
 
-	# Native COMPAT unavailable (or opt-out via ARMBIAN_PREFER_NATIVE_ARMHF=no).
+	# Native COMPAT unavailable (or opt-out via PREFER_NATIVE_ARMHF=no).
 	# Trust existing qemu-arm registration only if it actually executes —
 	# `enabled` flag alone doesn't tell us the interpreter is runnable
 	# (stale path, removed package). Validate via arch-test.