For the build machine I used the specs are g++ 4.9.1 on Ubuntu 14.10.
In some cases stdio.h seems to include getopt.h ("#if defined __USE_XOPEN && !defined __USE_XOPEN2K && !defined __USE_GNU") but I don't know if that is happening here. Are you building with a Mac or something?
Anyhow, it's probably something with the compiler, since he also auto-guesses the missing type to be int.
Not sure I completely understood the part about limited set of contributors. IANAL but I liked Ben Matlock on TV - if you are thinking of dual licensing GPLv3 with another license, you can do it as long as you hold the copyright, for other contributors you would require a CLA from them transferring their copyrights to you or specifically allowing you to dual-license their contributions or whatever. Of course anyone could now fork the sources as they are released and under GPLv3.
PS. For studying git, I might recommend http://git-scm.com/book/en/v2
, it has nice pictures and costs nothing to read online. Chapter 3 is most important, especially 3.2, 3.3 and 3.4.