[rtmpdump] [PATCH 1/2] darwin dylibs should used twolevel_namespace and dynamic_lookup

[Scott D. Davilla]

>Can you please provide more explanation of what this patch does or 
>why it's needed?

 From 'man ld' on osx

"Two-level namespace
      By default all references resolved to a dynamic library record 
the library to which they were resolved. At runtime, dyld uses that 
infor-
      mation to directly resolve symobls.  The alternative is to use 
the -flat_namespace option.  With flat namespace, the library is not
      recorded.  At runtime, dyld will search each dynamic library in 
load order when resolving symbols. This is slower, but more like how 
other
      operating systems resolve symbols."

We have found that using flat_namespace also risks symbol collision 
with malformed libs.

The change from 'undefined suppress' to 'undefined dynamic' is 
required when using a twolevel_namespace.

This patch is not 'required' as the lib will fuction just fine as it 
is linked, the change just makes it more proper. Using flat_namespace 
was the old way (ie. 10.4SDK) to create dylibs. twolevel_namespace 
has replaced it and is still 10.4SDK compatible.

Scott