Issue 5

Related to issue #5.

* Fixing warning:
```
src/animatedmeshscenenode.cpp: In function ‘bool irr_IAnimatedMeshSceneNode_setFrameLoop(irr_IAnimatedMeshSceneNode*, int, int)’:
src/animatedmeshscenenode.cpp:78:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
```

* Fixing detection of `x86_64` with `uname`
* Adding `-fPIC` flag for `x86_64` shared library compilation.