initramfs-framework: Add exec module

This new module allow for easy execution of external scripts or
applications. It runs anything found in /exec.d directory in order and
in case of no scripts to be available, it opens a shell.

(From OE-Core rev: 9b98c97338b4c3f985eca572d6a1e21324fa0fbc)

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/initrdscripts/initramfs-framework/exec

@@ -0,0 +1,29 @@
+#!/bin/sh
+# Copyright (C) 2017 O.S. Systems Software LTDA.
+# Licensed on MIT
+
+EXEC_DIR=/exec.d  # place to look for modules
+
+exec_enabled() {
+	return 0
+}
+
+exec_run() {
+	if [ ! -d $EXEC_DIR ]; then
+		msg "No contents to exec in $EXEC_DIR. Starting shell ..."
+		sh
+	fi
+
+	# Load and run modules
+	for m in $EXEC_DIR/*; do
+		# Skip backup files
+		if [ "`echo $m | sed -e 's/\~$//'`" != "$m" ]; then
+			continue
+		fi
+
+		debug "Starting $m"
+
+		# process module
+		./$m
+	done
+}