http://blog.httrack.com/blog/2014/03/09/what-are-your-gcc-flags/, https://news.ycombinator.com/item?id=7371806
dump all defines:
gcc -dM -E - < /dev/null
dump config (including build-in include paths):
gcc -E -x c++ - -v < /dev/null
static linking: http://stackoverflow.com/questions/4156055/gcc-static-linking-only-some-libraries/17712841#17712841