dynlib: optionally pass RTLD_GLOBAL to dlopen

Hi. 

I had to pass RTLD_GLOBAL to dlopen, to make python FFI work, because python packages need to access symbols in the python .so. I made this a flag for dynLib.loadLib.

I haven't run the test suite, since I don't know how. If you let me know how to run the test suite, I'll run it and report the results.