Assuming you're building off of the master branch, you'll be getting SFML 3, which is still in development and has some breaking changes. One change is that by default we're building static libraries (-s suffix) now.
If you want to get dynamic libraries (no -s suffix), you need to check the
BUILD_SHARED_LIBS option.
We also highly recommend to use something like the
SFML CMake Template that will automatically pull in SFML and build it for you within your project.