ld.so fix for empty LD_PRELOAD

[Stefan Sperling]

$ export LD_PRELOAD='' 
$ sed
sed: can't load library ''
$ env
env: can't load library ''
$ vim
/usr/local/bin/vim: can't load library ''
$ 

Is this the right way to fix it?

Index: loader.c
===================================================================
RCS file: /cvs/src/libexec/ld.so/loader.c,v
retrieving revision 1.120
diff -u -p -r1.120 loader.c
--- loader.c    25 Oct 2010 20:34:44 -0000      1.120
+++ loader.c    16 Dec 2010 21:40:07 -0000
@@ -493,7 +493,7 @@ _dl_boot(const char **argv, char **envp,
        TAILQ_INSERT_TAIL(&_dlopened_child_list, n, next_sib);
        exe_obj->opencount++;
 
-       if (_dl_preload != NULL)
+       if (_dl_preload != NULL && _dl_preload[0] != '\0')
                _dl_dopreload(_dl_preload);
 
        _dl_load_dep_libs(exe_obj, exe_obj->obj_flags, 1);