linux-next: add linux-headers make dependency (MR 5475)

The host tool compiled from drivers/tty/vt/conmakehash.c requires
linux/limits.h header which is not included (correctly?) inside the
kernel source tree and is instead needed to be installed on the host.

While this might not be totally correct, we need to get the package
building to avoid blocking all aarch64 packages from getting published
on our build system.

Also while we're at it, sort the list of make dependencies.

[ci:skip-vercheck]

device/testing/linux-next/APKBUILD

@@ -25,11 +25,12 @@ makedepends="
 	devicepkg-dev
 	findutils
 	flex
+	git
+	linux-headers
 	openssl-dev
 	perl
-	zstd
-	git
 	python3
+	zstd
 "
 builddir="$srcdir/linux-next-next-$_nextver"