add feature to trace native func

[tfewfew]

my project need a func to get callgraph, but it omit the native func cause it doesn't has call-graph in jar, but we need know which is native func while analyzing.
i think it's a nice func and i modifed the code to get that feature

[tfewfew]

i have finished the code and test, i'll pull the code later , pls check pull request, tks