Build different jni code (into different obj and libs directories) for
the different release/debug and xw4/xw4dbg combinations. This works when
only one build is done, but when doing two some later task tries to put
both multiple same-named libraries into the .apk and so fails. I still
think it's worth adding this to keep from using the wrong binary, but
that needs to be fixed.
cleanNDK just nukes all the directories. Easier than invoking build-ndk
clean...
Merging of AndroidManifest.xml files meant the dbg flavor was getting
its C2D_MESSAGE permission and the main flavor's, which on recent OS
versions meant it couldn't be installed. Use substitution from gradle to
fix.
