FIX: [droid] allow to build without debugging and pickup jenkins configuration

/cc @Memphiz @wsnipex @Montellese 
When doing, e.g. ```release: DEBUG=--enable-debug=no $(SOURCE)/libxbmc.so```
I get ```No rule to make target `release'```

Am I missing something?
This is with GNU Make 3.81, if it matters.