Fix incorrect use of variable arguments in run_parts() and simplify code

The run_parts() implementation used variable arguments in a bad way,
resulting in it not working properly.  Replaced va_*() code with a
simple cmd argument that's passed to each script called.

Also, the opendir()/readdir() code has been replaced with scandir()
using regular alphasort(). This simplifies the code somewhat as well.

Otherwise, minor cleanups.

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

svc.c

@@ -325,7 +325,7 @@ int svc_start(svc_t *svc)
 
 		if (debug) {
 			int fd;
-			char buf[256] = "";
+			char buf[CMD_SIZE] = "";
 
 			fd = open (CONSOLE, O_WRONLY | O_APPEND);
 			if (-1 != fd) {