Make building / running on FreeBSD easier

[johnae]

I know spook runs on FreeBSD 11 now. However building and running it could be more straightforward. The steps to make it run are:

1. Install gmake and gcc48
2. export CC=/usr/local/bin/gcc48
3. export LD_LIBRARY_PATH=/usr/local/lib/gcc48
4. gmake clean-deps; gmake clean ## just make sure spook artifacts are all cleaned out
5. gmake
6. run spook

It only runs properly as long as the LD_LIBRARY_PATH is set as above.

[johnae]

By the way, it might work fine with any version of gcc.

[johnae]

There's no reason I know of why it wouldn't build fine with clang like it does on OS X. Will investigate at some point.

[johnae]

As of 7050b70 this should work fine (since I've now got a freebsd laptop). Added instructions to README which basically boils down to:

install gmake
link cc to gcc (eg. clang is linked to gcc), more specifically:

sudo pkg install gmake
ln -s /usr/bin/cc /usr/local/bin/gcc
gmake

No need to install gcc.