make: filter /dev/null, optimize output

$(DEPS) idea from kbuild fixdep

1 files changed, 2 insertions, 2 deletions

diff --git a/make b/make
index 09433f7..58d6152 100755
--- a/make
+++ b/make
@@ -35,8 +35,8 @@ gen_dir_ents() {
 gen_depfile() {
     awk -v f=/dev/fd/3 -v deps="cpio_list.txt make" '
         { print }
-        $1 == "file" { deps=deps " " $3; print $3 ":" > f }
-        END { print "initramfs.img: " deps > f }
+        $1 == "file" && $3 != "/dev/null" { deps=deps " " $3 }
+        END { print "DEPS = " deps "\n$(DEPS):\ninitramfs.img: $(DEPS)" > f }
     '
 }