patch for module function probe

[Li Guanglei]

bibo mao :
> If it is designed feature, then kernel.function("foo") will be regarded 
> as module("kernel").function("foo").  But if there is one module named 
> "kernel.ko", how to probe its function although its module name is 
> weird?  In another way to say what is the meaning of 
> module("kernel").function("foo"), else stap manual clarify that 
> module("kernel") means kernel image, user had better not use the same 
> module name.

I tried and found:
module("kernel").function("foo") == kernel.function("foo"), which 
seems not appropriate.

I once thought module("*").function("foo") would be expanded as:
   module("aaa").function("foo")
   module("bbb").function("foo")
   module("kernel").function("foo")  // if happened to have a module 
named module which also has a function named foo
   ...
   kernel.function("foo")

That is to day, it should first search all loaded modules for function 
foo, then at last it will also search kernel image for function foo. 
So we need to change the current way it works with module("*").