Squashed 'tremendous/libfab/' changes from c0d71c0..b25d1bf

b25d1bf Merge pull request #2 from ryansb/tup
cd09046 use $(PREFIX) instead of hard coding usr/local
ea362b5 actually have the makefile build the .so
cda0174 add info about tup
c1b47f9 add Tupfile
03afe51 Define _GNU_SOURCE conditionally
REVERT: c0d71c0 Get initial working version of FFI bindings. No python API yet

git-subtree-dir: tremendous/libfab
git-subtree-split: b25d1bf6dfc3d911108d4a5bfa1971b85bd8ee16
Update subtree of libfab