Your game should do absolutely ok, and there is no simple way to get rid of the warning that I know of (trust me I tried).
The warning message comes from historical reasons. I believe it has been completely removed from the GCC 4.5 sources, but we're not using this yet.
For the record, the issue is that the mangling of 'va_list' has changed between gcc 4.2.1 and 4.4.0 (due to a late corrigenda to the ARM spec, previous versions of the toolchain mangled va_list the same a void*, which was wrong).
This however does *not* affect NDK-generated code because, very fortunately, none of the stable ABIs exposed by the NDK depend on this mangling (this has been checked carefully), so whichever toolchain you use, your code will run on all Android systems. This is very fortunate because GCC 4.4.0 does *not* provide a way to implement the old mangling (shrug). I guess ABI stability was not exactly their focus when they did the change.
However, please update your code if it doesn't build with 4.4.0, because we're really going to get rid of 4.2.1 in the future :-)
Hope this helps