scripts: warn if subpackage files can not be found

scripts/build/termux_create_debian_subpackages.sh

@@ -47,6 +47,8 @@ termux_create_debian_subpackages() {
 				# Add the -L clause to handle relative symbolic links:
 				mkdir -p "$SUB_PKG_MASSAGE_DIR/$_INCLUDE_DIRSET"
 				mv "$includeset" "$SUB_PKG_MASSAGE_DIR/$_INCLUDE_DIRSET"
+			else
+				echo "WARNING: tried to add $includeset to subpackage, but could not find it"
 			fi
 		done
 		shopt -u globstar extglob