Fix android build

Ensure your NDK_MODULE_PATH is correctly setup.
On Mac OS X, I do the following in ~/.bash_profile (create it if it doesn't exist):

```
export NDK_MODULE_PATH=~/code:~/code/nui4
PATH=${PATH}:~/code/ndk
```

Ensure it points to the correct location (I use nui4 locally). Note that PATH is updated to include the ndk directory.

Things to note about this commit:
3 functions have been added since linker would not find these symbols:

```
src/Application/Android/nglKernel_Android.cpp: nglKernel::SysInit()
src/Time/Android/nglTimer_Android.cpp: nglTimer::GetTimeOut() and nglTimer::Update()
src/Window/Android/nglWindow_Android.cpp: nglWindow::GetStatusBarSize()
```

They are not filled in and will assert if called.

```ndk-build -j 8``` is your friend on multi-core build machines :)