spdlog is header only library.
Just copy the files to your build tree and use a C++11 compiler

Tested on:
gcc 4.8.1 and above
clang 3.5
Visual Studio 2013

gcc 4.8 flags: --std==c++11 -pthread -O3 -flto -Wl,--no-as-needed
gcc 4.9 flags: --std=c++11 -pthread -O3 -flto


see the makefile in the example folder