Use PLATFORM variables in copy commands.
Move all exports to a sepperate env-setup.sh file

This way, you can use

  source env-setup.sh <ndk-path>
  pushd $TMPDIR
  $TOPDIR/build-droid/build-<project>.sh

to build a specific project.
You then still need to manually copy the needed libraries from
$TMPDIR/build/.../lib
Add PROTOBUF_VERSION

see protobuf branch
Upd README: add how to build a specific project
Add protobuf for droid
Merge branch 'env_setup' into my_master
Merge branch 'protobuf' into my_master

Conflicts:
	build-droid/build-all.sh