fix: ensure src-old is always removed on exit

apatch

@@ -1,5 +1,11 @@
 #!/bin/sh
 
+cleanup() {
+  rm -rf src-old
+}
+
+trap 'cleanup' EXIT INT HUP
+
 startdir="$PWD"
 
 [ -f APKBUILD ] || ( echo "please run this in a package directory"; exit 1 )
@@ -32,4 +38,3 @@ done
 )
 
 busybox diff -U3 -r "src-old$builddir" "src$builddir" | sed "s|src-old$builddir|a|g;s|src$builddir|b|g" > $1
-rm -rf src-old