To compile Hashcat you need to cross compile the gmp library for Linux (32/64 bit), Windows (32/64 bit) and OSX (64 bit). (see below)
First get a copy of Hashcat repository
$ git clone https://github.com/hashcat/hashcat.git
Install the dependencies
$ cd hashcat
$ sudo ./tools/deps.sh
Run make depending on your os
$ make [linux|osx|windows]
Not specifying an argument will build for all OSes except FreeBSD.
If you want FreeBSD binaries, you will need to run this on a native FreeBSD amd64 system
$ make freebsd
This has been tested on FreeBSD 10.2 and will produce ./hashcat-cli64.elf. You will need gmp installed (/usr/ports/math/gmp).
Enjoy your fresh Hashcat binaries ;)