[gambit-list] compiling libgambit.a for android

I added a small bash script on github

https://github.com/dmalves/compile-gambit-for-android

to help on the compilation of gambit for android. Using gambit 4.7.0 there are no errors, and it does compile to x86, arm and mips, creating a directory for each of the architectures.

I tested using the emulator and it worked for all architectures.

I loved alvatar's scheme sphere project on github. Maybe I could help a little, coz I am (when time is on my side) developing an app using gambit on android.

Anyway, I'll be making that script better, it is a mess now. Maybe it should have some command line arguments to tell what version to compile, what optimizations to use or maybe download gambit source if not available in current directory.