* simple_game: Configure Make and makefile for Linux environments

* simple_game: Fix build issues on Android plaform with Linux HOST

The Makefile.Android.linux file was out of date with the rest of the
project, so this commit updates the paths, as well as leaving some as
optional, if it is already configured as an environment variable.

In addition, it corrects the build error related to static raylib:
the makefile was trying to generate libmain.so using the path of the
NDK libraries, instead of using those of the Android system, which
resulted in crashes in the generated apk.