kbuild: handle compressed cpio initramfs-es

Make kbuild handle compressed cpio initramfs-es.  An already compressed
cpio is copied directly to usr/, while a non-compressed cpio is filtered
through gzip (no changes here) on its way to usr/.

If the user has created a compressed cpio by other means, this saves him
from uncompressing it, just to be compressed again by kbuild.
Signed-off-by: Alex Landau <landau.alex@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

scripts/gen_initramfs_list.sh

@@ -191,9 +191,10 @@ input_file() {
 	source="$1"
 	if [ -f "$1" ]; then
 		${dep_list}header "$1"
-		is_cpio="$(echo "$1" | sed 's/^.*\.cpio/cpio/')"
+		is_cpio="$(echo "$1" | sed 's/^.*\.cpio\(\..*\)\?/cpio/')"
 		if [ $2 -eq 0 -a ${is_cpio} == "cpio" ]; then
 			cpio_file=$1
+			echo "$1" | grep -q '^.*\.cpio\..*' && is_cpio_compressed="compressed"
 			[ ! -z ${dep_list} ] && echo "$1"
 			return 0
 		fi
@@ -223,6 +224,7 @@ cpio_file=
 cpio_list=
 output="/dev/stdout"
 output_file=""
+is_cpio_compressed=
 
 arg="$1"
 case "$arg" in
@@ -282,7 +284,11 @@ if [ ! -z ${output_file} ]; then
 		cpio_tfile=${cpio_file}
 	fi
 	rm ${cpio_list}
+	if [ "${is_cpio_compressed}" = "compressed" ]; then
+		cat ${cpio_tfile} > ${output_file}
+	else
 		cat ${cpio_tfile} | gzip -f -9 - > ${output_file}
+	fi
 	[ -z ${cpio_file} ] && rm ${cpio_tfile}
 fi
 exit 0