Java array length (using # operator/__len metamethod) and ignore some warnings

I needed the ability to use the # operator on arrays passed down from Java. It's a pretty simple change, and I've tested it and it works.

As a bonus, I hate seeing warnings, so I found the GCC pragma that asks it to ignore the warnings in question.

I also have extensions allowing LuaJava to access LuaJIT's FFI. Let me know if you're interested in adding that; FFI is awesome, and works on Android to pull in and link with .so files (as well as standard C library functions, of course -- I got rid of several calls into Java entirely by using FFI calls into C libraries, which is just all kinds of faster).

--Tim