busybox filesystem add ldd function

/********************************************************************
 *               busybox filesystem add ldd function
 * 聲明：
 *     本文主要是爲了解決繆新建提出的查看程序涉及到動態連接庫的問題。
 *
 *                                 2016-1-23 深圳 南山平山村 曾劍鋒
 *******************************************************************/

1、參考文章：
    where is 'ldd'?
        http://buildroot-busybox.2317881.n4.nabble.com/where-is-ldd-td48070.html

2、解決辦法：
    1. You really don't need a special ldd. ldd is just a script. In its most basic usage (ldd <executable>), it just runs: 
        # LD_TRACE_LOADED_OBJECTS=1 <executable> 
    2. For example on busybox: 
        # LD_TRACE_LOADED_OBJECTS=1 /bin/busybox 
            linux-vdso32.so.1 =>  (0x00100000) 
            libc.so.6 => /lib/libc.so.6 (0x0fe70000) 
            /lib/ld.so.1 (0x48000000 

3、測試效果：
    [zengjf@root ]# LD_TRACE_LOADED_OBJECTS=1 /bin/busybox
            libm.so.6 => /lib/libm.so.6 (0x2ac8c000)
            libc.so.6 => /lib/libc.so.6 (0x2acf6000)
            /lib/ld-linux-armhf.so.3 (0x2aae1000)
    [zengjf@root ]# LD_TRACE_LOADED_OBJECTS=1 /bin/main
    hello world.
    [zengjf@root ]# ls
    main    mainso
    [zengjf@root ]# LD_TRACE_LOADED_OBJECTS=1 /bin/mainso
            libc.so.6 => /lib/libc.so.6 (0x2abea000)
            /lib/ld-linux-armhf.so.3 (0x2ab1b000)
    [zengjf@root ]#