run(): add support for logging/redirect

This patch adds support for optional logging of output from all run()
commands.  For run_interactive() we've opted to log instead of just
redirect, meaning output on error is till on console but also in log.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/finit.c

@@ -333,7 +333,7 @@ static void fs_mount_all(void)
 	_d("Calling extra mount hook, after mount -a ...");
 	plugin_run_hooks(HOOK_MOUNT_POST);
 
-	run("swapon -ea");
+	run("swapon -ea", "swapon");
 
 	_d("Finalize, ensure common file systems are available ...");
 	fs_finalize();