build: Honour QUIET when cleaning

Author: mpe

build/scripts/clean.sh

@@ -13,4 +13,8 @@ IFS=@ read -r task subarch distro version <<< "$1"
 
 output_dir=$(get_output_dir "$script_base" "$subarch" "$distro" "$version" "$task" "$DEFCONFIG" "$TARGETS" "$CLANG" "")
 
-(set -x ; rm -rf "$output_dir")
+if [[ -n $QUIET ]]; then
+    rm -rf "$output_dir"
+else
+    (set -x ; rm -rf "$output_dir")
+fi