Thanks for all of the help, but I figured it out. I feel really dumb. I was referencing the include file for the Solarus build instead of the library (I think that's what its called). So it should be:
cmake -DSOLARUS_INCLUDE_DIR=~/solarus-1.4/include -DSOLARUS_LIBRARY=~/solarus-1.4/build/libsolarus.so ..
cmake -DSOLARUS_INCLUDE_DIR=~/solarus-1.4/include -DSOLARUS_LIBRARY=~/solarus-1.4/build/libsolarus.so ..